Companion

Companion was a somewhat vague term used to describe the Doctor's closest friends. (AUDIO: Situation Vacant, No Place Like Home, Death and the Queen) Such people knew the Doctor's "secret": that they were someone non-human who travelled in time and space in a police box-shaped craft called the TARDIS. The Doctor's companions often directly saved the Doctor's lives (TV: Rose, The Family of Blood) or provided the Doctor with a perspective that prevented them from abusing their Time Lord powers. (AUDIO: To the Death; TV: School Reunion, The Runaway Bride, The Fires of Pompeii) On some occasions, they were the proximate reason that the Doctor sacrificed their then-current life and regenerated. (TV: The Caves of Androzani, The Parting of the Ways, The End of Time) On others, they lost their lives in pursuit of the Doctor's goals. (TV: "The Traitors", "The Destruction of Time", Earthshock, Voyage of the Damned, Face the Raven; AUDIO: Absolution, To the Death)

The Eleventh Doctor told Amy Pond he travelled with companions to see the universe through the eyes of somebody who hadn't experienced it all already. (HOMEVID: Meanwhile in the TARDIS) He also mentioned that he took great care in choosing them. (TV: Amy's Choice) Once they left the Doctor's company, most companions used their newfound perspective of life and morality to help others; Sarah Jane Smith once noted that with them around "the Doctor" - their ideology and legacy - would never die. (TV: Death of the Doctor) Rose Tyler felt she had learned a "better way of living life" from her time spent with the Ninth Doctor, and earned a new resolve to take action, to make a stand when things needed changing. (TV: The Parting of the Ways) The companions also helped the Doctor in their battles against evil throughout time and space. (TV: The Ultimate Foe) In particular, Ace called the Daleks "the catch" to being a companion, (AUDIO: Enemy of the Daleks) while Clara Oswald described them as a companion's deadliest foe. (PROSE: ''The Companion's Companion)

Because the term was a shortening of the expression "travelling companion", most companions did in fact voyage with the Doctor in the TARDIS. Depending on the situation, other words were used to describe the same relationship — most frequently, "assistant". However, it was unusual to hear the Doctor call their friends by either word. Different incarnations had different preferences. The Third Doctor, perhaps owing to his unique situation of exile, most frequently used the term "assistant". (TV: The Ambassadors of Death, Terror of the Autons) On the other hand, when the Eighth Doctor was forced to define the word companion, he eschewed the term assistant in favour of friend. (AUDIO: Situation Vacant) Sarah Jane once implied the Doctor's companions served as a surrogate family for them, despite the Time Lord's insistence that they were alone in the universe. (TV: Journey's End) Martha Jones even stated the Doctor took on companions to ease their loneliness. (TV: The Family of Blood)

Both terms were occasionally troublesome. Sometimes, the word companion was interpreted sexually, leading to confusion about the Doctor's relationship with their friends. (TV: Aliens of London, Closing Time) Sometimes, companions bickered over the appropriateness of the word assistant. Rose Tyler said emphatically, "I'm not his assistant" when Sarah Jane Smith called her one. (TV: School Reunion) Rose seemed happier being called a "companion", as when Harriet Jones called out over the Sub-Wave Network for "former companions of the Doctor". (TV: The Stolen Earth)

Another term was associate, which was used primarily by the Daleks. (TV: The Parting of the Ways, The Big Bang, The Witch's Familiar) The Eleventh Doctor himself once introduced Clara Oswald to Mother Superious Tasha Lem as his associate. (TV: The Time of the Doctor)

People were companions or assistants to the Doctor for varying lengths of time, but most stayed with him for more than one adventure. (TV: An Unearthly Child, The Daleks, The Rescue, The Romans, The Chase, The Time Meddler et al.) Some stayed for a few days, while others were with them for years. (AUDIO: No Place Like Home, Absent Friends) On occasion, companions could be separated from the Doctor for months or years before they resumed travelling with them. (TV: The Doctor, the Widow and the Wardrobe, AUDIO: The Juggernauts) Other Time Lords, usually renegades, sometimes had travelling companions.

Humans
In the main, the Doctor travelled with humans, mostly from the 20th and 21st centuries. (TV: "An Unearthly Child", "Bell of Doom", The War Machines, The Wheel in Space, Rose, Dalek, School Reunion et al.) Their fondness for humans was one of the reasons they were exiled to Earth by the Time Lords. (TV: The War Games) Despite the Doctor claiming to be all alone, Sarah Jane Smith told the Tenth Doctor that he had the biggest family in the universe: them. (TV: Journey's End)

Most of the Doctor's human companions were from either the mid-late 20th century (TV: "An Unearthly Child", "Bell of Doom", The War Machines, The Time Warrior et al.) or the early 21st century. (TV: Rose, Smith and Jones, Partners in Crime et al.) The vast majority of companions from this time period were either English or picked up by the Doctor in England. There were exceptions to this, however. The American Peri Brown met the Doctor whilst holidaying in Lanzarote. (TV: Planet of Fire)

Gender
Amongst the Doctor's human companions, a high number of them were young women — a fact the Eleventh Doctor once tried sheepishly to hide from Amy Pond. (HOMEVID: Meanwhile in the TARDIS)



It was the First Doctor who first had multiple adventures exclusively with a man from Earth, Steven Taylor. (TV: The Massacre, PROSE: Roses, Making History, Waiting for Jeremy) The Doctor's second incarnation was never long without Jamie McCrimmon at his side, (COMIC: Action in Exile - The Night Walkers, PROSE: World Game, Golem, Blue Road Dance, Scientific Adviser, That Time I Nearly Destroyed the World Whilst Looking for a Dress, Mother's Little Helper, Reunion, Dust) even after his trial with the Time Lords. (PROSE: The Time Eater, COMIC: Invasion of the Quarks to Martha the Mechanical Housemaid)

The Fifth Doctor also adventured with a World War II American pilot, Gus, (COMIC: 4-Dimensional Vistas - The Moderator) and the Eighth Doctor may have travelled solo with his long-term companion, Fitz Kreiner. (PROSE: Escape Velocity)

The Doctor's relationship with their companions usually remained platonic, though gender as well as sexuality could play a role in romantic or sexual feelings being harboured in either direction.

The Eighth Doctor described beginning to feeling sexual and romantic urges for the first time, but found it important to stress to I.M. Foreman that it wouldn’t be fair on any of his companions for them to get involved with him. (PROSE: Interference - Book Two)

Despite this acknowledged power dynamic, (PROSE: Interference - Book Two) there were some encounters between the Eighth Doctor and his companions. In fact, Bernice Summerfield recalled having sex with him soon after his regeneration. (AUDIO: Benny's Story, PROSE: The Dying Days)

The Ninth and Tenth Doctors shared a relationship with Rose Tyler which appeared romantic to outside observers, such as Mickey Smith, (TV: Boom Town, School Reunion, Rise of the Cybermen, Doomsday) Martha Jones (TV: The Sound of Drums) and Donna Noble. (TV: Journey's End)

Later on, the Eleventh Doctor married his on-and-off companion River Song, in a ceremony both parties recognised as binding, (TV: The Wedding of River Song, The Angels Take Manhattan, The Husbands of River Song, HOMEVID: Last Night et al.) and which carried through to the Doctor’s other incarnations, even as they met out of order. (TV: The Husbands of River Song, AUDIO: My Dinner with Andrew)

Romantic feelings were not always reciprocated. Martha Jones was in love with the Doctor but was rebuffed. (TV: Last of the Time Lords) Equally, Amy Pond was sexually interested in the Doctor but was firmly rejected. (TV: Flesh and Stone) When exposed to a Truth Field in the presence of the Eleventh Doctor, Clara Oswald blurted out "I'm an English teacher from the planet Earth, and I've run off with a man from space because I really fancy..." She cut herself off and covered her mouth. (TV: The Time of the Doctor) The Twelfth Doctor admitted that he had thought of himself in some sense as Clara's boyfriend while in his eleventh incarnation. (TV: Deep Breath)

In Amy Pond and Rory Williams, the Eleventh Doctor had a married couple aboard the TARDIS. (TV: A Christmas Carol et al.) Rory sometimes had doubts as to whether Amy preferred the Doctor over him, leading to some tension. (TV: Day of the Moon) When Jo Jones found out about Amy and Rory, she felt embarrassed for having left the Third Doctor in order to get married to her husband Cliff Jones. (TV: Death of the Doctor)

Non-humans
Despite a statistical preference for humans, the Doctor had non-human companions or at the very least, companions who were not from Earth or descended from its people. This included the First Doctor's earliest companion, Badger, an Avatroid that helped raise him as a childe in the House of Lungbarrow.

The non-human companions the Doctor travelled with usually had the outward appearance of a human or Time Lord. On at least three occasions they travelled with members of their own species. The longest serving were his granddaughter Susan Foreman, (TV: An Unearthly Child et al.) Romana, (TV: The Ribos Operation, et al.) and John and Gillian Who. (COMIC: The Klepton Parasites) Lady Serena was significant as well, for sacrificing her life in service to the Doctor's goals. (PROSE: World Game) Other human-like individuals with whom they adventured included, but certainly weren't limited to: Trakenite Nyssa, (TV: Logopolis) Alzarian Adric, (TV: Full Circle) Trion Vislor Turlough (TV: Mawdryn Undead) and Astrid Peth from Sto. (TV: Voyage of the Damned)

On occasion, they were accompanied by obviously non-human species, like Whifferdills, (COMIC: The Shape Shifter) Ice Warriors, (COMIC: Descendance) Oblivioners, (COMIC: Bad Blood) Eutermesans, (AUDIO: The Creed of the Kromon) Vessicans (COMIC: Thinktwice) and cyber-converted humans. (COMIC: The Company of Thieves) During her time working for the Division, the Fugitive Doctor had a Lupar companion named Karvanista. (TV: Once, Upon Time, The Vanquishers) The Fourteenth Doctor briefly formed a companionship with a pig, whom he named Alfredo. (PROSE: Under Control)

Artificial life-forms sometimes travelled with the Doctor, as well. Clearly, K9 was the Doctor's most-beloved robotic companion, given the number of models the Doctor built (TV: The Invasion of Time, School Reunion, A Girl's Best Friend) and the pleasure the Tenth Doctor displayed when he re-encountered a version of the robot. (TV: School Reunion, The Wedding of Sarah Jane Smith) The Doctor seemed empathetic to artificial life-forms with errors in their programming. The Fifth Doctor once effectively euthanised an android companion in irremediable distress. (TV: Planet of Fire)

Shortly before his time on Trenzalore, the Eleventh Doctor obtained a Cyberman head he named "Handles". Handles aided him greatly with technological assistance, being his only real companion during his first three hundred years on Trenzalore as he'd sent Clara Oswald home and everyone he cared about that lived there eventually died. After three hundred years, Handles died of old age, reducing the Doctor to tears. (TV: The Time of the Doctor)

The Twelfth Doctor teamed up with a Dalek named Lumpy to collect the Orb of Fates and stop the Daleks, Cybermen and Sontarans from controlling the Starbane. However, it turned out that Lumpy had tricked the Doctor at the very beginning of the adventure. (GAME: The Doctor and the Dalek) His later companion, Nardole, was humanoid, but explicitly not human - he was at least partially cybernetic, (TV: The Pilot) harboured a distaste for humans, (TV: Smile, The Doctor Falls) and was only "human enough" because the Doctor had gotten his lungs cheap. (TV: The Pyramid at the End of the World)

Joining the Doctor
The Doctor began relationships with their companions in a great variety of ways. Some, like Adric, (TV: State of Decay) Leela, (TV: The Face of Evil) Tara, (COMIC: Official Secrets) and Zoe, (TV: The Wheel in Space) stowed away on the TARDIS, fully aware it was a ship that could take them away from their home. Others, like Ian Chesterton, Barbara Wright (TV: "An Unearthly Child") and Dodo Chaplet, (TV: "Bell of Doom") were taken away without their consent. They were also occasionally assigned assistants by those in nominal authority over him. During his exile on Earth, the Third Doctor's assistants were mostly supplied by the Brigadier. (TV: Spearhead from Space, Terror of the Autons) In the case of UNIT soldiers, the Doctor worked with whomever the Brigadier happened to have on duty at the time of a crisis. This was how he first met Mike Yates. (PROSE: The Eye of the Giant) The Doctor's other "bosses" — the Time Lords (PROSE: World Game, AUDIO: Blood of the Daleks) and the White Guardian (TV: The Ribos Operation) — also occasionally provided companions, invariably against the Doctor's wishes. Even the Daleks understood that he was commonly assisted by companions. For example, when the Daleks abducted the Eleventh Doctor for a mission regarding the Dalek Asylum, they also abducted his most recent companions, Amy Pond and Rory Williams, to assist him. (TV: Asylum of the Daleks) Much like the UNIT soldiers that worked with the Doctor as assistants under her father, Kate Stewart tended to help the Doctor on Earth when the situation brought them together. (TV: The Power of Three, The Day of the Doctor, The Magician's Apprentice, The Zygon Invasion/The Zygon Inversion, The Vanquishers) However, while helping to stop The Master's Dalek Plan, Kate briefly travelled in and even piloted the TARDIS, although it was made clear that this was the first time that she had ever stepped foot inside. Kate's constant help of the Doctor and her brief travel in the TARDIS appeared to grant her the status of companion as she was later invited by Graham O'Brien to a support group meeting of the Doctor's former companions. (TV: The Power of the Doctor)

All that said, the most common way of initiating TARDIS travel was to be invited by the Doctor. Although with some cases there was, from their perspective, a significant gap of time between first meeting of the Doctor and getting to travel with him, Donna Noble, (TV: The Runaway Bride, Partners in Crime) Amy Pond (TV: The Eleventh Hour) and Rory Williams (TV: The Eleventh Hour, The Vampires of Venice) were companions who began travelling at the Doctor's request a significant amount of time after they first met. In most cases there was little to no time gap between meeting the Doctor and getting to travel with them, Clara Oswald, (TV: The Bells of Saint John) Martha Jones, (TV: Smith and Jones) Rose Tyler, (TV: Rose) Jack Harkness, (TV: The Doctor Dances) Ace, (TV: Dragonfire) Vislor Turlough, (TV: Mawdryn Undead) Izzy Sinclair, (COMIC: Endgame) Charley Pollard, (AUDIO: Storm Warning) Arnold, (COMIC: Children of the Evil Eye) Jamie McCrimmon, (TV: The Highlanders) Victoria Waterfield, (TV: The Evil of the Daleks) Vicki (TV: "Desperate Measures") and others all began their travels with the Doctor because he asked them. Mickey Smith became a companion by asking the Doctor if he could travel with him, rather than the other way around. (TV: School Reunion)

Other companions "forced" their way into the TARDIS. Leela, despite the Fourth Doctor's protests, ran into the TARDIS and, before he could shoo her out, fiddled with the controls, causing it to dematerialise. (TV: The Face of Evil)

Rarely, the Doctor invited people to travel with them, like Lynda Moss, (TV: The Parting of the Ways) Astrid Peth (TV: Voyage of the Damned) and Rita, (TV: The God Complex) only to have their death prevent their travels. The same thing happened with Clara Oswin Oswald, although the Doctor found out that there was another version of her somewhere in time and space and set out to find her. (TV: The Snowmen)

Leaving the Doctor
People left the Doctor for reasons as varied as the reasons they first walked through the TARDIS doors. They were of three broad types: the companion wanted to leave; (TV: "The Planet of Decision", "Horse of Destruction", The Savages, The War Machines, Last of the Time Lords) the Doctor wanted the companion to leave; (TV: "Flashpoint", The Long Game, Utopia, The God Complex) or some external force compelled the companion and Doctor to separate. (TV: "The Traitors", "The Destruction of Time", The War Games, The Hand of Fear, Earthshock, Doomsday, The Angels Take Manhattan, Hell Bent)

When asked by Brian Williams, father to one of their companions, Rory Williams, and father-in-law to Amy Pond, another companion, what happened to the people who travelled with them, the Eleventh Doctor explained that some left him, some got left behind, and also admitted that "not many, but some" died. (TV: The Power of Three) The Sixth Doctor confided in Jack Harkness, who was abandoned by the Ninth Doctor, that he did it to "the best of [their] companions and the robot dog." (AUDIO: Piece of Mind)

The companion's choice
The choice to leave was sometimes the companion's.

A common reason for the departure of female human companions was romance. Sometimes, as with Vicki, (TV: "Horse of Destruction") Jo (TV: The Green Death) and Leela, (TV: The Invasion of Time) they left to get married, while at least one companion, Martha Jones, left partly because she realised her romantic feelings for the Tenth Doctor would never be reciprocated. (TV: Last of the Time Lords) On other occasions, the Doctor travelled with married couples in the TARDIS, most notably Amy Pond and Rory Williams. (TV: The Big Bang et al.) In the Doctor's youth, before they had established reasonable control over the TARDIS, companions sometimes left, at least in part, because they happened to have access to their own time period and wanted to return home. This was especially true of the companions who had not actually chosen to travel with the Doctor, such as Ian and Barbara, (TV: The Planet of Decision) Dodo, (TV: The War Machines) and Polly and Ben. (TV: The Faceless Ones) However, this sometimes happened later in the Doctor's life. Ly-Chee, for instance, thought the Seventh Doctor was only offering him a lift into town. Instead, they had several adventures together. When the TARDIS finally deposited him in the correct town, he headed for the nearest pub and ordered a stiff drink without once looking back. (COMIC: The Enlightenment of Ly-Chee the Wise)

Some companions left to improve a particular society they had encountered with the Doctor. Nyssa left to help cure Lazar's disease, (TV: Terminus) whilst Steven Taylor stayed on the planet of the Elders to be its leader. (TV: The Savages) Likewise, Romana II chose to remain in E-Space to help the Tharil species. (TV: Warriors' Gate) Tara Mishra left the Ninth Doctor after wishing to stay and help with the disaster aftermath on Nomicae, (COMIC: The Bidding War) though both parties made it explicit that this was temporary, and Jack Harkness was sent to collect her after some time. (COMIC: The Lost Dimension) Later, Mickey Smith deliberately stayed in the parallel Pete's World to help its citizens defeat the Cybermen and to support his grandmother's living parallel counterpart. (TV: The Age of Steel) Mickey proved especially independent when it came to departing the Doctor's side; he later left the TARDIS again, this time to return to his "home" Earth, ultimately to defend it from alien threats. (TV: Journey's End, The End of Time)

Others left for more personal improvement. Melanie Bush parted ways from the Seventh Doctor purely to have new adventures in space — but not time — with Sabalom Glitz. (TV: Dragonfire) Frobisher left the Doctor to enjoy the pleasure planet A-Lux. (COMIC: A Cold Day in Hell!) Liz Shaw left UNIT and the Third Doctor to return to her research, telling the Brigadier that all the Doctor needed in an assistant was "someone to pass him his test tubes and tell him how brilliant he was". (TV: Terror of the Autons) After another brief adventure on Messaline Martha Jones declined to travel with the Doctor again wishing to be a part of UNIT. (TV: The Doctor's Daughter)

Some companions left simply because they no longer enjoyed travelling with the Doctor. Victoria Waterfield left because she had grown tired of the continual danger in which she found herself and decided to choose a safer new life. (TV: Fury from the Deep) Tegan Jovanka similarly left because she had become sickened by the death and destruction she witnessed. (TV: Resurrection of the Daleks) Likewise, Dan Lewis made the choice to leave following a near death experience. (TV: The Power of the Doctor)

Because they were Earth-based assistants who either never wanted to travel with the Doctor on a long-term basis or never were invited to do so, a few companions made only a single journey or two, but otherwise provided significant assistance from Earth. The Brigadier (TV: The Invasion, The Five Doctors) and Wilfred Mott (TV: The Stolen Earth, The End of Time) were classic examples of this sort of assistant, but Maxwell Edison (COMIC: Stars Fell on Stockbridge) and, for a time, Mickey Smith (TV: Aliens of London/World War Three, School Reunion, The Girl in the Fireplace) could be viewed in this light as well. Harry Sullivan also left the Doctor to return to his usual life after a single trip in the TARDIS, (TV: Terror of the Zygons) albeit one punctuated by several detours by other means.

One companion who briefly left by her choice was Clara Oswald. After a trip to the Moon in which she was forced to decide whether to kill an innocent creature or to save planet Earth, the Twelfth Doctor refused to help, Clara grew so angry she left the TARDIS, telling the Doctor never to come and find her again. (TV: Kill the Moon) However, with the help of Danny Pink, she realised she wasn't ready to give up the Doctor yet and agreed to a final trip with him weeks later to the Orient Express at which point she decided to permanently rejoin him despite the dangers and the coldness the Doctor once again displayed on the trip. (TV: Mummy on the Orient Express) Clara again left the TARDIS after Danny's death, under the mistaken belief that the Doctor had found his home planet of Gallifrey, while the Doctor believed that Danny was alive and with Clara. (TV: Death in Heaven) Later, the Doctor returned to save her life, in an adventure in which both lies were exposed. Afterwards, the Doctor gave Clara one more invitation to join him again, and she accepted. (TV: Last Christmas)

The Doctor's choice
Sometimes companions were kicked out of the TARDIS, either as punishment or for the companion's personal growth. Adam Mitchell was summarily tossed out after he was found trying to use his trip into the future to alter his own fortunes. (TV: The Long Game)

Susan, (TV: "Flashpoint") Arnold, (COMIC: The Amateur) John and Gillian (COMIC: Invasion of the Quarks) were more charitably dismissed. The Doctor clearly believed he was doing them good by ending their travels. The Doctor prevented these youths from continuing to travel with them because he felt it would interfere with their natural maturation. Married couple Amy and Rory were returned home by the Eleventh Doctor, who feared for their lives if they continued on their travels. (TV: The God Complex) The Twelfth Doctor left Clara Oswald home after believing she'd gotten her dead boyfriend Danny Pink back from the Nethersphere and would be happy with him. (TV: Death in Heaven) As the Thirteenth Doctor prepared to regenerate, she returned Yasmin Khan home, deciding to face her next incarnation alone. (TV: The Power of the Doctor)

Separation by situation
There were occasions when the Doctor and their companions were separated more by circumstance than the wishes of either party. Perhaps the most obvious case of this was when the Tenth Doctor and Rose Tyler were separated by the closure of the walls between dimensions. (TV: Doomsday) Sarah Jane Smith's departure occurred because the Fourth Doctor was summoned to Gallifrey (TV: The Hand of Fear) at a moment in Gallifreyan history when humans weren't allowed on the planet. (TV: School Reunion) The Time Lords forced Zoe and Jamie to part from the Second Doctor, with only the memories of their first adventure with him intact. (TV: The War Games) The Time Lords later claimed they had developed this procedure into a "standard response" for companions with whom they dealt. The Sixth Doctor, for instance, encountered a version of Peri Brown who had been given "the Jamie and Zoe treatment". She retained memories only of the adventure with the Fifth Doctor, Turlough and which began on Lanzarote. (AUDIO: Peri and the Piscon Paradox) Finally, whilst in his tenth body, the Doctor had to stabilise the effects of a biologically untenable combination of his DNA with Donna Noble's. To do so, he had to submerge all memories of her time with him and shield her from those memories lest she die. Thus, although he did, in a sense, kick her out of the TARDIS for her own good, neither wanted it. (TV: Journey's End) She did briefly remember snippets of her travels but was knocked unconscious by it and then forgot again. (TV: The End of Time) Similarly, Donna's consciousness was saved to The Library against her will, causing her to forget about the Doctor and spending years from her point of view married to Lee McAvoy. This was only temporary, however, and soon afterwards she resumed her travels. (TV: Silence in the Library / Forest of the Dead)

Jack Harkness' days in the TARDIS came to an end in similarly unusual circumstances. Because he had died and been resurrected by Rose as the Bad Wolf entity, he became, in the words of the Tenth Doctor "just wrong". No longer able to die, he was instead a kind of "fixed point in time" which the TARDIS herself rejected. (TV: Utopia) Nevertheless, the Doctor re-invited him on board the TARDIS (TV: Last of the Time Lords) and he later travelled aboard it without apparent difficulty. (TV: Journey's End) However, on both occasions, he was more interested in pursuing a life with Torchwood Three than returning to the Doctor's side on a long-term basis.

Amy Pond and Rory Williams were sent back in time by a Weeping Angel, separating them from the Eleventh Doctor for the remainder of their lives. They both died at age 87 and 82 respectively. (TV: The Angels Take Manhattan)

Death
Some companions died, often in service to the Doctor's goals. Katarina (TV: "The Traitors") and Sara Kingdom (TV: "The Destruction of Time") both died to prevent the Daleks obtaining taranium. Adric sacrificed himself trying to stop a prehistoric Cyberman invasion of Earth. (TV: Earthshock) Roz Forrester died in battle. (PROSE: So Vile a Sin) Lucie Miller and Tamsin Drew were both killed whilst defeating the Dalek Time Controller's invasion of Earth in the late 22nd century. (AUDIO: To the Death) Astrid Peth died killing Max Capricorn. Her atoms were left to travel the universe. Without her sacrifice, the Tenth Doctor would not have regained control of the Titanic, nor prevented it from having a costly collision into Buckingham Palace. (TV: Voyage of the Damned, Turn Left)

Cinder, who was briefly a companion of the War Doctor, sacrificed her life to save the Doctor when the Time Lord Karlax tried to kill him under orders from Rassilon. It was for fear of this highly probable eventuality of a companion's death that the War Doctor was reluctant to let a companion join him during his years of fighting in the Last Great Time War. He gave Cinder a proper burial and promised to end the Time War to honour her sacrifice. (PROSE: Engines of War)

Three unusual cases were those of Peri Brown, Ace and River Song.

Peri was killed by King Yrcanos on Thoros Beta, whilst her body was being subjected to Crozier's troubling body-swapping experimentations. For a time, the Sixth Doctor believed Peri had died. At the conclusion of his second major trial by the Time Lords, however, the Inquisitor revealed Peri's death had likely been a trick of the Valeyard. The Inquisitor showed the Doctor that Peri, far from being killed by Yrcanos, had, in fact, married him. (TV: Mindwarp) However, at a later date, the Time Lords revealed their meddling with Peri's timestreams had resulted in multiple versions of Peri running around the cosmos. One of these Peris had been killed by Yrcanos, as the Doctor originally believed. (AUDIO: Peri and the Piscon Paradox) Like Peri, Ace died young according to two accounts, but not others. According to one, she died while using Nitro-9 against parasitic beings known as the Lobri. Her sacrifice saved the lives of Sarah Jane, Susan, Peri and the Seventh Doctor. (COMIC: Ground Zero) In another account she was killed by George Limb, only to be replaced by a divergent version of herself, who continued to travel with the Doctor and who only had superficial differences from her other self. (PROSE: Loving the Alien) Furthermore, according to other accounts, she lived to a much older age — at least into her late thirties and fifties. (PROSE: Set Piece, At Childhood's End, et al.)

River Song died physically when she linked her mind into the CAL computer during the Doctor's first meeting with her -- from his perspective; from hers, it was the last of many following an unspecified period of time as his companion. (TV: Forest of the Dead) Unknown to the Tenth Doctor, River was part Time Lord due to having been conceived on board the TARDIS by the Doctor's future companions Amy Pond and Rory Williams, but had given up her future regenerations to save the Eleventh Doctor's life. (TV: A Good Man Goes to War, Let's Kill Hitler) The Doctor, therefore, proceeded with his timeline knowing how River would one day die. He gave her a sonic screwdriver specially designed to save her mental patterns at the moment of her death in the Library. (TV: The Husbands of River Song) This allowed the earlier Tenth Doctor to upload River into CAL's immense memory bank, allowing her to live on in the computer. (TV: Forest of the Dead) She later managed to somehow link herself into a psychic "conference call" from inside CAL even as a data ghost to aid the Doctor one last time on Trenzalore before fading forever after he finally said goodbye to her. (TV: The Name of the Doctor)

Kamelion, an android companion, was destroyed by the Fifth Doctor in an act of mercy per Kamelion's own request after it was taken over by. (TV: Planet of Fire)

Clara Oswald, a companion of the Eleventh and Twelfth Doctors, sacrificed herself for Rigsy, whom she had only met once before. She was killed by a Quantum Shade after saying goodbye to the Time Lord, with the Doctor ultimately blaming Ashildr for her death. (TV: Face the Raven) The Twelfth Doctor extracted her from her timestream moments before her death using Time Lord technology, although she was frozen in between one heartbeat and her last. He realised that they couldn't continue travelling together as the prophecies of the Hybrid would come to pass, so he planned to erase Clara's memories of him with a neural block. However, upon discovering this, Clara attempted to reverse the polarity of the neural block so it would affect the Doctor, something he doubted had worked when she told him. They agreed to activate the device together, not knowing which one of them would be affected, and it affected the Doctor. Clara left in a stolen TARDIS with Ashildr to travel the universe before returning to Gallifrey and dying. (TV: Hell Bent)

Unknown reasons
Very rarely, it was unknown what caused certain companions to stop travelling with the Doctor.

In the case of the Earthbound Third Doctor, relationship timings with his occasional assistants became very unclear. Assistants in this period didn't stop travelling with him; his exile on Earth made it impossible for them to start travelling with him. (TV: Spearhead from Space - The Three Doctors) Assistants during this period tended to be people who lived in England (TV: Spearhead from Space, Terror of the Autons) whom he could meet in Bessie. Since he wasn't housing companions in the TARDIS, there wasn't a definite "moment" when an assistant entered or left "the TARDIS team". Therefore, incomplete records existed as to how long the Doctor knew certain assistants. It was never known, for example, definitively when the Doctor met or said goodbye to Tom Phipps and Joe. (COMIC: The Vortex, Fogbound) Similarly, it was never known how the Fourth Doctor met or parted with Joan Brown (COMIC: Doomcloud) or Young. (COMIC: The Sea Devil)

A similar situation occurred when the Eleventh Doctor had to guard Trenzalore for hundreds of years. Individuals such as Theol Willoughby who acted as companions did not enter or leave the TARDIS team, not least because the TARDIS was travelling in the Time Vortex for a prolonged period of time without him. Due to the extended lifespan of the Doctor, he outlived the inhabitants of the town making it impossible to determine when exactly they became companions. (TV: The Time of the Doctor, PROSE: An Apple a Day...)

The influence of Gallifrey
The Fourth Doctor lost four consecutive companions to the direct or indirect influence of Gallifrey: he was forced to leave Sarah Jane Smith on Earth on receiving an emergency summons; (TV: The Hand of Fear) Leela and K9 Mark I chose to stay on Gallifrey; (TV: The Invasion of Time) and Romana II, who had been summoned to return to Gallifrey (TV: Full Circle) escaped by remaining in E-Space with K9 Mark II. (TV: Warriors' Gate) The Sixth Doctor was also unable to save Peri Brown, being transported away by the Time Lords at a crucial moment. (TV: Mindwarp)

The warden of the Twelfth Doctor's confession dial, the Veil, was actually a benevolent being, trying to help the Doctor escape during his imprisonment. It came to see itself as his companion, hoping the Doctor would take it with him to what laid beyond the dial. However, because he was unaware of the Veil's true nature, (PROSE: The Veil) the Doctor displayed no sadness when the being died. (TV: Heaven Sent)

Balancing travels and home
"We have two lives. Real life and Doctor life. Except real life doesn't get much of a look in."

- Rory Williams

After joining the Ninth Doctor on his travels, Rose Tyler made what was intended to be a quick stop home to see her mother, Jackie Tyler. However, they found that the TARDIS had taken them 12 months after Rose left, rather than the intended 12 hours. (TV: Aliens of London) After being embroiled in the London UFO crash, Rose left with the Doctor again. Though she told Jackie that she could be back within 10 seconds, she did not return after that time elapsed. (TV: World War Three) Infact, Rose would be away from home for extended periods of time as she continued travelling with the Doctor. (TV: Boom Town, The Parting of the Ways) Following his regeneration, the Tenth Doctor returned to the Powell Estate with Rose on Christmas Eve. (TV: The Christmas Invasion) Following Christmas, Rose resumed her travels with the Doctor, being seen off by Jackie. (TV: New Earth) Jackie told Elton Pope that Rose called her now and then but not as often as she liked, and admitted that she felt "left behind". (TV: Love & Monsters)

Martha Jones, a medical student who joined the Doctor for "one trip" in the TARDIS, (TV: Smith and Jones) was eventually returned home 12 hours after she had left, only to rejoin the Doctor that same day after the pair confronted Richard Lazarus. (TV: The Lazarus Experiment) Soon after, she made a phone call to her mother, Francine Jones, who told her that it was election day. (TV: 42) Upon returning home using Jack Harkness' vortex manipulator after the TARDIS was stolen by, Martha found that it was the day after the election, only four days after she had met the Doctor. (TV: The Sound of Drums)

Romance
In one future stemming from the Eighth Doctor's life, (PROSE: The Tomorrow Window) the Ninth Doctor was engaged to be married to Emma, the only travelling companion he had ever "had". However, an incident which caused the Doctor to undergo four regenerations in quick succession resulted in Emma calling off her marriage to the female Thirteenth Doctor. (TV: The Curse of Fatal Death)

Understanding that Jack Harkness was "just a bit more flexible when it [came] to dancing", the Ninth Doctor posed the question of who he would like to "dance" with, himself or Rose Tyler. (TV: The Empty Child) Before facing a Dalek attack on the Game Station, Jack gave the Doctor a goodbye kiss. (TV: The Parting of the Ways) Having been "abandoned" by the Doctor, (AUDIO: Piece of Mind) Jack was recorded as saying that, when he found the Doctor, he would kiss him before killing him. (TV: Fragments) When he saw that Martha Jones "fancied" the Tenth Doctor, Jack asked "you too, huh?" (TV: The Sound of Drums) Mistakenly believing Graham O'Brien to be a new incarnation of the Doctor, Jack described him as "still sexy". (TV: Fugitive of the Judoon)

Martha Jones grew to fall in love with the Doctor as she travelled with him, (TV: The Sound of Drums) and it was her knowledge that he would not reciprocate her feelings that led her to leave the TARDIS for home, as well as the impact the The Year That Never Was had on her family. (TV: Last of the Time Lords)

Acknowledging that his time with Martha got "complicated", the Doctor told Donna Noble that he just wanted "a mate". Donna, who had misheard the Doctor as saying that he wanted "to mate", expressing her disgust and rejection of such a prospect. (TV: Partners in Crime) The Doctor and Donna were mistaken for a married couple on multiple instances, a misconception which they were quick to correct. (TV: The Fires of Pompeii, Planet of the Ood, The Unicorn and the Wasp)

The Master
Other Time Lords had companions in their travels. Before his final corruption into the renegade known as, the Time Lord Koschei was accompanied in his hunt for the Doctor by Ailla. Koschei believed Ailla to be a young woman from a 28th century Earth colony, but she was, in fact, a Time Lady agent sent by the High Council to spy on his increasingly erratic behaviour. (PROSE: The Dark Path)

that joined with Tremas had control over Kamelion for a time. He used him to escape Xeriphas and to impersonate King John. However, the Doctor freed him from the Master's control and invited him to join the TARDIS crew, which he did. (TV: The King's Demons) The Master later regained control over him, causing Kamelion to persuade the Doctor to destroy him. (TV: Planet of Fire)

The Tremas Master also briefly bribed Sabalom Glitz to help him in his schemes and betray the Doctor although the Master was tricked by the Valeyard, ending his plan. (TV: The Ultimate Foe) According to one account, Christopher Marlowe's death was prevented by the Master who took him away from Deptford shortly before he was scheduled to die. He travelled with the Master for some time before returning and accepting his fate. (PROSE: Master Faustus) This Master also possessed an Auton duplicate that obeyed his commands. (GAME: Destiny of the Doctors, HOMEVID: Destiny of the Doctors)

In his battle with the newly regenerated Eighth Doctor, was assisted by Chang Lee, a young man in 1999 San Francisco. Lee had been convinced by the Master that the Doctor was evil. Only too late did he learn the truth when the Master killed the boy, although the TARDIS subsequently restored him to life. (TV: Doctor Who)

During the Last Great Time War, the Master took on Cole Jarnish as a companion. (AUDIO: The Good Master) However, this was nothing more than a ruse and he killed him once his usefulness had come to an end. (AUDIO: The Heavenly Paradigm), the Master worked with Chantho, who in many ways could be considered his companion. However, after regaining memories of his previous incarnations, the Master killed Chantho. (TV: Utopia)

took the Time Lord-companion relationship one step further by marrying his human companion Lucy Saxon, with every indication a passionate relationship existed between them, (TV: The Sound of Drums) only for it to turn physically abusive, culminating in Lucy shooting and apparently killing her husband. (TV: Last of the Time Lords, The End of Time)

As part of a test of the Missy incarnation of the Master's redeemed goodness, the Twelfth Doctor sent her on a mission with his own companions Bill Potts and Nardole acting as Missy's companions. (TV: World Enough and Time), while furthering the Kasaavin invasion, collaborated with Daniel Barton, who travelled with him in his TARDIS. (TV: Spyfall)

Iris Wildthyme
The relationships between transtemporal adventuress, Iris Wildthyme, and her companions wasn't particularly complex (excluding the order of the companions; that is unambiguously contradictory). (PROSE: Wandering Stars, et al.)

Her companions varied significantly in appearance and personality, such as "butch dyke traffic warden" Jenny Winterleaf; (PROSE: Verdigris, Bafflement and Devotion, et al.) erudite art critic Panda; (AUDIO: Wildthyme at Large, PROSE: Wandering Stars, Death of the Author, et al.) author Paul Magrs (PROSE: Bafflement and Devotion, Party Fears Two, The Magrs Conundrum!, et al.) and his partner, Jeremy; (PROSE: The Scarlet Empress, Party Fears Two) and retired Mexican luchador, Señor 105. (PROSE: Iris Wildthyme y Señor Cientocinco contra Los Monstruos del Fiesta, Deleted Scene from 'Iris Wildthyme and the Key Lime Pie 2 Time' - 'Part 3: The Stones of Blood' , et al.)

Others
When she left the Fourth Doctor in E-Space, Romana II was accompanied by K9 Mark II. (TV: Warriors' Gate) K9 continued as her companion after she returned to Normal Space. (WC: Shada, et al.) After returning to Gallifrey, Romana shared numerous adventures alongside one of the Doctor's former companions, Leela. (AUDIO: Gallifrey) In her fourth incarnation, Romana travelled with Ponch. (PROSE: Tomb of Valdemar)

Renegade Time Lords in the part-time employ of the Celestial Intervention Agency often adopted Doctoresque lifestyles, complete with companions — only a few of whom had typically been assigned to them by the CIA as mission partners. Rollo's included fellow Time Lords Verika and Volusa, as well as a variety of humans from miscellaneous time-periods, such as Erin Grant, Jim Waters, Michael Duncan, David Smythe, Steven Reynart, Jody Lockhart, and, potentially, Julia Fraser and Thomas Carruthers. (GAME: )

Sometime after leaving the Doctor, Lucie Miller travelled with the Monk, apparently after responding to an advert that he placed in 2010 for a companion. (AUDIO: Situation Vacant) He later abandoned Lucie, instead, convincing Tamsin Drew, the Doctor's current companion, to leave the Doctor and join him instead. (AUDIO: The Resurrection of Mars)

During the War in Heaven, it became commonplace for Time Lords to take their humanoid type 103 TARDISes as companions; (PROSE: Alien Bodies) equally, from another point of view, the time ships were taking their pilots as companions. (PROSE: The Book of the War) Homunculette travelled with Marie in this way. (PROSE: Alien Bodies)

In the City of the Saved, Grandfather Halfling went on extended trips to the outside universe with Amanda Legend Lefcourt (PROSE: The Book of the War) and Melicia Clutterbuck. (PROSE: Of the City of the Saved...)

Companions of non-Time Lords
After being cut off from the caldera, the 102-form timeship Compassion had multiple time sensitive companions to act as her power source. (PROSE: Warring States) These included the Gallifreyan technician Nivet (PROSE: The Ancestor Cell) and the enigmatic Carmen Yeh. (PROSE: The Book of the War)

When Elizabeth Klein rewrote history using the Doctor's stolen TARDIS to ensure the existence of the Third Reich into the future, she was given the position of head of Temporal Affairs. In this capacity, she travelled in the TARDIS with Major Richter, although it was an open secret that he was there to both learn how to use the TARDIS himself and ensure that Klein's loyalties remained with the Reich rather than risk her sympathising with the aliens she encountered. (AUDIO: The Architects of History)

Mister Saldaamir had companions, who were destroyed in the Time Wars alongside his homeworld and the rest of his kind. (PROSE: Mr Saldaamir)

Time travelling DJ Theo Possible travelled for long periods of time with Kelsey, (PROSE: Party Kill Accelerator!) Steve, (PROSE: Happily Ever After Is a High-Risk Strategy) and Queenie Tilbury. (COMIC: The Train in Vain and the Junkmail Messiah)

Jackson Lake, while believing himself to be the Doctor, had Rosita as his companion. In fact the real Doctor, in his tenth incarnation initially considered himself to be Jackson's companion. Rosita continued as Jackson's companion even after his memory and original personality were restored, being hired by Jackson to act as the nursemaid for his son Frederic Lake. (TV: The Next Doctor)

Jack Harkness compared his relationship with Angelo Colasanto to that of the Doctor and his companions. (TV: Immortal Sins) When his attempt to fill in the role of the Doctor landed him in trouble, Jack received assistance from the Sixth Doctor, who played the part of "Captain Jack Harkness". (AUDIO: Piece of Mind) Jack's relationship with Gwen Cooper as he took her under his wing to introduce her to Torchwood also had a Doctor-companion undertone. (TV: Everything Changes)

Sarah Jane Smith developed her own cohort of companions during her time based out of 13 Bannerman Road. These included her adopted children Luke (TV: Invasion of the Bane) and Sky (TV: Sky) and several local teenagers who came and went over time: Maria Jackson, (TV: Invasion of the Bane, The Last Sontaran) Clyde Langer, (TV: Revenge of the Slitheen) Rani Chandra (TV: The Day of the Clown) and Kelsey Hooper. (TV: Invasion of the Bane) She also had two non-human companions: K9 Mark IV and the alien supercomputer Mr Smith. (TV: Invasion of the Bane)

When the Torchwood of Pete's World launched a search via dimension cannon to find the Tenth Doctor in N-Space, Rose Tyler volunteered to lead the search through the parallel universes. Though her first venture was made alone for safety reasons, Rose endangered her own life to take that universe's Clive Finch, whose N-Space counterpart she had known, back with her. Now knowing that two people could use the dimension cannon at a time, Rose justified her actions by recruiting Clive to accompany her (AUDIO: The Endless Night) in the next trip. (AUDIO: The Flood) In the third, Rose was accompanied by Pete Tyler, the eponymous counterpart of her deceased father in Pete's World. (AUDIO: Ghost Machines) In the fourth, Rose was accompanied by her own mother, Jackie Tyler. (AUDIO: The Lasty Party of Earth)

It could be argued that Ashildr and Willa Twiston are Clara Oswald's companions when she got hold of her own American diner TARDIS. (TV: Hell Bent; PROSE: The Witchfinders)

Behind the scenes

 * It is unknown what exactly caused the Eighth Doctor's companion Destrii's departure from the TARDIS. The start of the Ninth Doctor's era on television meant that the Eighth Doctor comics were coming to an end. With a reluctance to kill her off in her final appearance in the strip she simply stopped appearing. Destrii reappeared in The Stockbridge Showdown although her departure remained unaddressed.

What does the word "companion" actually mean?
The term "companion" is used more outside the programme — which is to say in fandom — than within the narrative. It was especially rarely used in the original version of the television programme. While the First Doctor referred to Ian Chesterton as "one of [his] companions" as early as The Daleks, it was practically never uttered by the Doctor himself until the John Nathan-Turner producership. "Assistant" was a far more common designation — being used, for instance, by the First Doctor to describe Dodo Chaplet in The War Machines, by the Brigadier to introduce Jo Grant in Terror of the Autons and by the Fifth Doctor to jog the Brig's memory of Jo in Mawdryn Undead. However, "companion" has been heard with greater regularity in other media — particularly that written since the transmission of Survival.

Indeed, Big Finish Productions have an entire range of product called The Companion Chronicles, which focuses on telling Doctor Who adventures from the perspective of the assistant. Equally, Doctor Who Magazine have taken to labelling the role that of "companion" — as they did on the cover of DWM 446, when they announced the arrival of Jenna-Louise Coleman. The tacit assumption between DWM editors and their readers is that, somehow, both groups know what the other is talking about — as if the word companion were a title whose qualifications and responsibilities were well defined. However, this is not the case.

Neither assistant nor companion have ever been unambiguously defined in a narrative. Without a solid in-universe definition, viewers are left to struggle with the term on their own. At what point, they are forced to ask themselves, does a supporting character become a "companion"? Is it when they travel in the TARDIS? If so, then Liz Shaw isn't a companion, despite being the clear co-star of an entire season. Is it when they're in more than one story? If so, then Sara Kingdom, Christina de Souza, Jackson Lake, Adelaide Brooke, Wilfred Mott and Astrid Peth must be struck from the list, despite the fact that their respective actors were given star billing in their respective episodes (Kingdom excluded as she was featured in a 1960s story, long before "star billing"). Can Jackie Tyler be considered a companion, since she appeared in numerous stories and she travelled in the TARDIS, and she even helped the Doctor recover after a regeneration?

Meta-fictional and story considerations are also a problem. Canton Everett Delaware III spent three months assisting the Doctor, travelled in the TARDIS at least once, and encountered him again forty years later, yet lack of star billing and the fact his time with the Doctor is shown over only two episodes puts his status in dispute.

Then there are behind-the-scenes concerns. If an actor like Jean Marsh tells us flatly that she was not hired as a companion (BFX: The Drowned World, DOC: From Kingdom to Queen) and the official BBC website's own list of companions does not include her, is it reasonable to consider Sara Kingdom a companion? If her, why not Bret Vyon, who also appeared in several episodes of TV: The Daleks' Master Plan fulfilling a function nearly identical to Sara? In a similar vein, the early story TV: The Keys of Marinus features two characters, Altos and Sabetha, who non-ambiguously joined the TARDIS crew as companions for the course of the single adventure, although they never rode in the TARDIS itself; do they have as valid a claim to being companions as Christina de Souza, who likewise never set foot in the TARDIS during her single adventure?

This question can be expanded to the literally hundreds of characters depicted on TV, in comic strips and in literature who over the years have filled companion-like roles in one-off stories as they encountered the Doctor. Indeed some of these characters have been promoted to ersatz companion status. For a time, Henry Gordon Jago and George Litefoot could be described as just this; one-off characters from TV: The Talons of Weng-Chiang who, decades later, were featured in an edition of the Big Finish Productions audio series, The Companion Chronicles, and later given their own spin-off series. However, they travelled with the Sixth Doctor in AUDIO: Voyage to Venus and Voyage to the New World, making their status as companions less controversial.

All these question marks! Determining who is a companion and who is not is one of the most common fan debates. It is possible by the fact that the television programme itself offers no definition for the term. Though probably exacerbated by the BBC Wales version's greater narrative flexibility, the debate is hardly a new one. It's been going on for ages, fuelled in previous decades by officially licensed reference works that helped mould fan opinion. For instance, the Brigadier, one of the people whose companion status is most hotly contested, gets some support for his alleged "companion status" from the book The Making of Doctor Who, in which two of the main writers of his era of the programme unambiguously called him a companion. Likewise, the later John Nathan-Turner book, The Companions was influential in making 1980s fans remember Sara Kingdom and for enshrining her as a companion — albeit against evidence in the BBC archives.

Still, though the new series put the term "companion" on more solid narrative ground, it greatly confuses the definition. ". . . what constitutes a Doctor Who companion is no longer clear. Sure, Rose, Martha and Donna were all companions. So was Captain Jack. But what about Mickey and Jackie? How do you qualify? Name in the opening credits, regular trips in the Tardis? The Doctor kisses you? I'm no longer sure. Modern TV drama is so difficult."

- Steven Brook, The Guardian

In truth, though, it's never been very clear, even from a behind-the-scenes perspective. Though BBC Wales have confused things by putting single-episode guest stars in the opening credits, the "classic" series sowed similar confusion by often not listing "companions" very high in the credit list. Any definition of companion as "co-star" falls apart in the classic era, because companions were often listed after guest stars — sometimes after several guest stars. And claims that they were "regulars" must be counterbalanced against the fact that they were often contracted only for a matter of weeks, and lived under the threat of being unceremoniously dismissed mid-serial, like Jackie Lane was.

Term as used on this wiki
This narrative uncertainty makes it difficult for this wiki to consistently use the term. Several forum debates have raged as to how the term should be applied, including Disputed Companions and Who counts as a companion?. Those readers wishing to understand why certain companions are included on certain lists that appear on this site may want to explore those discussions; however, the simplest expression is that we will, by and large, err on the side of inclusivity, and entertain any plausible arguments that X character "counts".

Televised longevity
In televised Doctor Who, actors who played companions rarely stayed more than a series. Though some companions had notably long runs, they were the exception more than the rule.

Discounting companions like Astrid Peth and Sara Kingdom — each of whom appeared in only a single story — the record-holder for the shortest run would be Adam Mitchell. He appeared in only two stories or about 90 minutes of televised Doctor Who, spread across eight days of real-world time. Record-holders for longest tenures can be measured in different ways. Special mention should also be given here to the character of the Brigadier, who was an incredibly long-serving member of the cast. Regular or not, the character as played by Nicholas Courtney appeared in more episodes of the programme than all of the 1980s Doctors except Tom Baker, from The Web of Fear Episode 3 on 17 February 1968 to Battlefield Part Four on 27 September 1989, 21 years and 7 months later.
 * In terms of individual episodes, Jamie McCrimmon is the easy winner with 113 episodes between The Highlanders and The War Games, outdistancing most Doctors, much less all other companions. He served for the better part of three seasons, during which Doctor Who had its highest episode count. Due to changed television consumption habits, that record will almost certainly never be approached, much less broken. (Note that the above number doesn't take into account episode 4 of The Enemy of the World where Jamie is still travelling with the Doctor but neither Frazer Hines nor Hamish Wilson appear on screen. Were that to be accounted for, Jamie would have two consecutive episode totals of 48 and 64, respectively. The total number increases to 116 if one includes his later return in The Two Doctors; Hines' appearance as Jamie in The Five Doctors is not included as he was only playing an apparition and not the actual character.)
 * In terms of stories, given that BBC Wales has a much higher story count (per season) compared to the original series, the high water mark has been set by Clara Oswald, appearing in 30 full-length televised stories from The Snowmen on 25 December 2012 to her exit in Hell Bent on 5 December 2015. Actor Jenna Coleman also appeared as an echo of Clara prior to The Snowmen in Asylum of the Daleks, and as part of the Testimony (Clara's memory) later on in Twice Upon a Time.
 * In terms of calendar time that the public would have perceived a character as being a regular on Doctor Who, the winner is Yasmin Khan, with a period of four years and 16 days from her first regular appearance in The Woman Who Fell to Earth on 7 October 2018 to her last regular appearance in The Power of the Doctor on 23 October 2022. Note that calendar years are not the same thing as seasons, as Doctor Who has not consistently begun its seasons on the same date or even month each year. Also, during Yasmin's tenure her three-series run aired in 2018, 2020, and 2021, with 2019 having a single New Year Special, Resolution, and her final three episodes in 2022 consisting of New Year Special Eve of the Daleks, Easter Special Legend of the Sea Devils, and BBC Centenary Special The Power of the Doctor.
 * In terms of length of incumbency, Ace is easily the record-holder, having joined the Doctor in 1987's Dragonfire (TV story) and ceasing to be the incumbent companion by default nine years later when the 1996 TV Movie depicted the Seventh Doctor traveling alone.
 * In terms of season count, Tegan Jovanka and Sarah Jane Smith are,, the only travelling companions to appear during four consecutive seasons as a regular, having appeared in seasons 18 to 21 and seasons 11 to 14 respectively. Only Jo Grant, Sarah Jane, and Yaz appeared in three complete seasons, namely seasons 8 to 10; seasons 11 to 13; and series 11 to 13 of the BBC Wales/BBC Studios revival series.