Companion




 * For a full list of the Doctor's companions see: List of companions.

Over the years, the Doctor has acquired numerous companions in his travels through space and time.

Overview
Some appear to have travelled with him for years, others for just a few days. While these companions have included members of various species from different planets, most have been humans from the planet Earth, especially the 20th and 21st centuries. Most of these, in turn, have been young females. The earliest known companion of the Doctor was Susan Foreman, who was his granddaughter and a fellow native of Gallifrey. He has also had at least one fellow Time Lord as a companion (Romana - it is not known whether Susan was considered a Time Lord during her travels with the Doctor). Not all of the Doctor's companions have been humanoid or even near-human. He has also travelled with K-9 Mark I and II, a shape-changing android (Kamelion) and a Whifferdill who preferred to maintain the form of an earth penguin (Frobisher), among others. One accounts shows the Doctor traveling with an android version of the Master (WC: Scream of the Shalka).

Not all Companions need to travel with the Doctor to be called a companion. Such cases are Sara Kingdom, Astrid Peth and Wilfred Mott

Use of the Term
The exact term used to describe these various friends of the Doctor has varied over the years, ranging from "friend" to "assistant" to "companion". Among the few uses of the term in an official sense were via former Prime Minister Harriet Jones when she activated the Sub-Wave Network and identified Martha Jones as "former companion of the Doctor" (DW: The Stolen Earth) and by Yvonne Hartman of Torchwood 1 who said "the Doctor and his companion" was the general pattern of the TARDIS crew. Jones also referred to the former companions of the the Doctor as "The Doctor's Secret Army" (DW: The Stolen Earth), while Dalek Caan referred to them as the Children of Time (DW: Journey's End).

Role of the Companion
The role of companions in the narrative vary. Usually, they play the role of stand-in for the audience by giving the Doctor a reason to explain what is happening in the story and what he is doing. In the case of the First Doctor who was more frail and older than his successors, male companions were included for the purpose of action scenes and to add a heroic element. Companions also often get into trouble requiring the Doctor to rescue them and, female companions in particular, have been noted for screaming in fear. A number of actors have expressed frustration at the limited nature of the companion role in the original series and this has been a factor in the decision of many female actors in particular not to extend their periods on the program. In the original series the companions who remained longest with the Doctor were Jamie McCrimmon, Sarah Jane Smith, Jo Grant and Tegan Jovanka.

The degree to which companions are developed varies. Russell T Davies is noted for giving companions more depth and making them into more important features of the program. In the new series, there has been extended exposition on both the impact the Doctor has on the lives of their companions and their emotional development while travelling with him as well as the lasting impact he has on their lives once they leave. A companion's reasons for joining the Doctor have also been given more attention. As well, the Doctor's need for companions, both in order to alleviate his loneliness and to help him keep his bearings and avoid going too far in his conflicts with aliens has also been explored. Under Davies' tenure, ongoing attention has been paid, for the first time, to a companion's family and the effect their travels with the Doctor have on them (this has in fact been the case with all three major companions since the series returned in 2005, with the family members also all taking major roles in some storylines). In previous eras, if a companion's family was seen at all, it would be in the story that introduced the companion and only on a couple of occasions were companions shown being returned to (more or less) their original departure location and time, unlike the Davies era which saw all three major companions returned directly to their families (albeit on a parallel Earth in the case of Rose Tyler).

In the original series, some attempts were made to depart from stereotypical depictions of female companions. Zoe Heriot was a mathematician and a genius whose technical knowledge was, in some instances, greater than the Doctor's. Liz Shaw was UNIT's scientific advisor who was on leave from Cambridge University. Sarah Jane Smith was a career woman whose initial interest in the Doctor stemmed from her profession as a journalist. Leela, her usually skimpy attire notwithstanding, was depicted as a deadly, athletic fighter. Romana was a fellow Time Lord whose academic record was superior to the Doctor's. Romana II, in particular, was depicted as very much the Doctor's equal and even shared the Fourth Doctor's sense of humour and whimsical nature, in contrast to the more austere Romana I. Finally, Nyssa was gifted in bioelectronics and had other advanced scientific knowledge and was one of the few companions capable of operating the TARDIS.

In some cases, companions take up the role of protecting the Earth when the Doctor is gone, such as in the case of Rose Tyler, Martha Jones, Jack Harkness and Sarah Jane Smith. It's also shown in the new series that while his companions alone could deal with some of the threats to Earth that the Doctor deals with, dealing with them alone can cost their lives. It also shows how important the Doctor is to the protection of Earth. In an alternate reality where the Doctor died and so many major threats happened, all of his companions died protecting the Earth and all that were left was an alternate Donna Noble and the correct Rose Tyler. Donna and Rose changed history to save the Doctor and the universe, with the alternate Donna even sacrificing herself to do so (DW: Turn Left).

It's also been shown that in some cases, the Doctor simply cannot save the day without the help of a companion. It took the aid of Rose Tyler, Jackie Tyler, Mickey Smith, Martha Jones, Jack Harkness, Sarah Jane Smith, the Meta-Crisis Tenth Doctor and Donna Noble to defeat Davros and his plans (DW: The Stolen Earth/Journey's End).

In the case of Wilfred Mott, he became a companion because The Woman had him seek out the Doctor. After finding him, Wilfred joined him in saving the universe. His role wasn't as active as other companions in activily battling the Doctor's enemies, but he lended much support to the Doctor from the sidelines. He gave the Doctor his gun (which proved vital in stopping Rassilon and his plans), gave him advice, acted as a gunner on an alien ship in order to buy the Doctor the time needed to reach the manision where the Master was and saved a man trapped in a radiation booth. Also, he fulfilled the prophecy of "he will knock four times" that would procced the Doctor's death and the Doctor made a conscious choice to save him, causing the Doctor to regenerate. After his one adventure with the Doctor, he returned home to his family without any signs of further interest in traveling with the dying Doctor. (DW: The End of Time)

Relationships
Most evidence indicates the Doctor's relationships with his companions have been platonic in nature. There have been some instances where a relationship between the Doctor and a companion may have developed beyond simple friendship, but the only confirmed case of this (to date) has been the relationship between the Doctor and Rose Tyler (DW: Doomsday, Journey's End). At least three companions have indicated they had fallen in love with the Doctor, although the Doctor did not appear to reciprocate: Sarah Jane Smith (DW: School Reunion), Jack Harkness (DW: Utopia, et al) and Martha Jones (Last of the Time Lords, et al). The Doctor, in his tenth incarnation, also encountered River Song, a woman from his personal future who claimed to have been not only a companion, but to also share a relationship with the Doctor intimate enough for him to tell her his real name (DW: Silence in the Library/Forest of the Dead).

The Doctor, for his part, once told Rose that he couldn't allow himself to develop such feelings, due to the reality that, as a Time Lord, he can expect to live for centuries, while a human companion would age and die. (DW: School Reunion) However, by the time Rose became trapped on Pete's World, the Doctor had changed this attitude, at least in terms of Rose; her subsequent loss to a parallel world sent the Doctor into an emotional tailspin halted by his later companionships with Donna Noble and Martha Jones. Despite the close friendships that developed, he remained emotionally distant from Martha in particular, despite (perhaps due to) her own direct professions of love for the Doctor; she eventually left him due to this (DW: Last of the Time Lords), although she remained close to him and would reunite with him on several occasions thereafter (DW: The Sontaran Strategem, Journey's End, IDW: Tesseract).

On at least two occasions the Doctor has invited individuals with whom he had fallen in love to become companions: Madame de Pompadour (DW: The Girl in the Fireplace) and Joan Redfern (DW: The Family of Blood). Circumstances prevented the former from doing so (though she had agreed), while the latter refused.

The Doctor, in his tenth incarnation, once stated that, of all his companions, the one he regretted leaving behind the most was his granddaughter, Susan. (IDW: The Forgotten) And he once confided to Jackson Lake that, ultimately, his heart is broken when a companion leaves him (DW: The Next Doctor).

Donna Noble stated that the reason the Doctor requires so many companions is too keep him from succumbing to his darker urges - to stop him, as it were. (DW: The Runaway Bride)

Recent incarnations of the Doctor have tried to improve companion safety by providing tools for communication and TARDIS access, including copies of the TARDIS key (which by the time of the Doctor's Ninth and Tenth incarnations could be seen as a symbol of having become a companion) and recent companions have also had their mobile phones upgraded to superphones by the Doctor, allowing communication with Earth and with the Doctor through time and space. This also has on at least two occasions allowed a former companion, Martha Jones, to contact the Doctor after leaving the TARDIS (DW: The Sontaran Strategem; IDW: Tesseract'').

The Tenth Doctor ends up developing a strong paternal relationship with his one-time companion Wilfred Mott that other charchters such as the Master even notice with the Master refering to Mott sarcasticaly as the Doctor's father. However, both Mott and the Doctor admit they'd be proud to be related to each other with the Doctor saying that it would have been an honor for him if Wilfred Mott was his father. At the end, both are willing to sacrifice themselves for each other: Mott being an old man is willing to die rather than have the Doctor absorb a lethal dose of radiation and be forced to regenerate which he doesn't want to do while the Doctor is willing (albeit a little reluctantly at first) to save Mott instead saying its his honor to save Wilfred. The Tenth Doctor ends up saving Mott at the expense of being fatally poisioned by radiation and is forced to regenerate into the Eleventh Doctor as a result. (DW: The End of Time)

The Tenth Doctor especialy develops a close relationship with each of his companions that he considers visiting each one and helping them in some small way to be his reward for everything he's done and spends an unknown amount of time traveling to visit each one of them before he regenerates: the Doctor rescues Martha Jones and Mickey Smith (now married) from a Sontaaran about to kill them, he saves Sarah Jane Smith's son Luke Smith from being hit by a car and waves goodbye to her, he visits Joan Redfern's granddaughter to see how her life was after he left, sets Jack Harkness up with Midshipman Alonzo Frame at a space bar, uses money borrowed from Geoff Noble in the past to buy a winning lottery tickey to secure Donna Noble's financial future as a wedding gift and visits Rose Tyler on New Years Eve 2005 and lets her know she's going to have a good year (meaning her travels with his ninth incarnation). (DW: The End of Time)

Non-Platonic Relationship
Also often debated is whether or not the Doctor took his relationship with any of his companions beyond friendship. Due to the original series' perceived status as a "children's program", any hint of romance between the Doctor and his companions was discouraged. One often-cited possibility is the relationship between Romana and the Fourth Doctor, especially in the hindsight of knowing the real-life romance between Lalla Ward and Tom Baker that blossomed during their tenure together (resulting in their brief marriage which began during a break in filming The Keeper of Traken). This is actually supported by an unusual source: a series of TV commercials Baker and Ward filmed for Australian TV in 1980; advertising Prime Computers, the ads featured The Doctor and Romana; the third ad showed Romana flirting romantically with the Doctor, and ends with the Doctor proposing marriage to her. These ads are not, of course, considered part of the canon.

The revelation in School Reunion that Sarah Jane Smith was indeed in love with the Doctor has led to further debates as to whether similar feelings were shared by other "classic series" companions. It was not until the 1996 telefilm that the Doctor was shown in an unambiguously romantic circumstance with a companion (albeit a one-off one), when he kisses Grace Holloway before departing (their first kiss can be attributed to the Doctor's excitement, though Grace subsequently says later in the film that she'd "fallen" for him). This was followed by the Doctor and Rose Tyler experiencing a form of romance which underscored the events of The Stolen Earth/Journey's End. In Rose's case, she likely ended up with the Meta-Crisis Tenth Doctor in alternate reality. In his case, he was part-human and would grow old and die, allowing Rose to grow old with an incarnation of the Doctor. In addition, Captain Jack Harkness, Martha Jones, Jackie Tyler, Astrid Peth and Christina da Souza have all expressed romantic or flirtatious feelings towards the Doctor. In most cases he did not reciprocate, although his Ninth incarnation indulged in some flirtatious banter with Harkness (though more to wind up Rose than anything else), and his Tenth did not protest overmuch when Astrid and Lady Christina kissed him. Donna Noble kissed the Tenth Doctor in The Unicorn and the Wasp, but this was in order to save his life, although her unambiguously states her desire to stay with the Doctor forever prior to her memory erasure in Journey's End. However, in Donna's case, she stated specificly that she was just a friend and refused to even consider a romantic relationship. The Eleventh Doctor and Amy Pond are in a romantic relationship as Amy kisses the doctor (DW: Flesh and Stone).

Joining the Doctor
Companions have come and gone in many different ways. Some, such as Rose Tyler, have been explicitly invited (DW: Rose); some have been unwilling adventurers, such as Ian Chesterton and Barbara Wright (DW: An Unearthly Child); while some have joined the TARDIS crew by accident, such as Dodo Chaplet (DW: The Massacre of St Bartholomew's Eve). A few individuals have been invited to join the Doctor in his travels, only to decline, such as Grace Holloway (DW: Doctor Who), Joan Redfern (DW: The Family of Blood), and (initially) Donna Noble (DW: The Runaway Bride); others, having been invited, were ultimately prevented from joining the Doctor due to their deaths, such as Lynda Moss (DW: The Parting of the Ways), Madame de Pompadour (DW: The Girl in the Fireplace), Astrid Peth (DW: Voyage of the Damned) and Jenny (DW: The Doctor's Daughter) - although in Jenny's case her "death" was only temporary though was still prevented from joining the Doctor in his travels (so she went off on her own instead). Jackson Lake qualified as a potential companion (especially given his knowledge of the Doctor's history), but as he had a son to take care of, so there's no indication the Doctor considered asking him to travel (DW: The Next Doctor).

On a few occasions an individual has asked to join the Doctor in his travels, only to be refused. Recent examples include Bayldon Copper (DW: Voyage of the Damned) and Christina de Souza (DW: Planet of the Dead). Amy Pond initially met the Doctor at the age of seven, and asked to join him on a trip. However, he delayed accepting her request due to the TARDIS being in need of urgent repairs and, as such, she was only accepted as a companion officially fourteen years later. (DW: The Eleventh Hour)

In one case, one of his companions, Wilfred Mott, activly sought him out at The Woman's insistance. Wilfred ended up joining him for one adventure and helped save the universe, but he had no desire to join full-time, was never asked and never did ask. (DW: The End of Time)

Leaving the Doctor
Companions have departed the Doctor for various reasons. Some have left after becoming disillusioned with the life of a time-traveller, such as Tegan Jovanka (DW: Resurrection of the Daleks), while a number of companions have departed in order to forge a new life in a new time or world, such as Vicki (DW: The Myth Makers), Mickey Smith (DW: The Age of Steel) and Susan Foreman (DW: The Dalek Invasion of Earth), although in the case of Susan the decision for her to stay was made by her grandfather. A few companions have left the Doctor due to Time Lord actions, such as Sarah Jane Smith (DW: The Hand of Fear) and Jamie McCrimmon (DW: The War Games). Only one companion has lost the privilege of travelling in the TARDIS: Adam Mitchell was evicted (DW: The Long Game) for bad behaviour. On a few rare occasions, companions have been killed while travelling with the Doctor, the first known fatality being Katarina (DW: The Daleks' Master Plan). Others who have died have included Sara Kingdom (also DW: The Daleks' Master Plan), Adric (DW: Earthshock) and Astrid Peth (DW: Voyage of the Damned). Another companion, Adelaide Brooke, committed suicide (DW: The Waters of Mars). At least two non-organic companions - Kamelion (DW: Planet of Fire) and K-9 Mark III (DW: School Reunion) have been destroyed. Several other companions have been killed but resurrected, including Jack Harkness (DW: The Parting of the Ways) and Grace Holloway (DW: Doctor Who (1996)). As noted above, one companion, Martha Jones, chose to leave because of the Doctor's unwillingness or inability to reciprocate romantic feelings (DW: Last of the Time Lords). In one unique circumstance, Donna Noble, while she did not die, was forced to forget her experiences with the Doctor in order to save her life (DW: Journey's End). In Wilfred Mott's case, he joined the Doctor for one adventure to save the Earth from the Master and later Rassilon, and was returned home by the Doctor prior to the Doctor's regeneration, with no indication as to whether ongoing travels were a possibility.

The departure circumstances of at least two companions, Ace and Destrii, have yet to be definitively chronicled, with differing accounts existing for the fate of Ace in particular.
 * Ace last appeared on TV in DW: Survival, and eventually left the Doctor in the novel NA: Set Piece, though she reunited with the Doctor a few times after that (most recently in NA: Lungbarrow); as the novels fall into a "grey area" of continuity, it's unknown whether this is the true chronicle of her fate (see also DWM: Ground Zero, a comic strip, the novelisation of The Curse of Fenric, and the webcast Death Comes to Time, each of which chronicles completely different fates for Ace). Destrii, a comic book companion, last appeared in DWM: The Flood but was dropped from the strip thereafter with no resolution when the comic strip jumped ahead to feature the adventures of the Ninth Doctor and Rose.

Rejoining the Doctor
After departing from a companion, the Doctor is rarely known to reunite with them, though there have been some exceptions, a few of them only brief returns, such as:
 * Susan Foreman (DW: The Five Doctors)
 * Sarah Jane Smith (DW: The Five Doctors, School Reunion, The Stolen Earth/Journey's End, The End of Time, SJA: The Wedding of Sarah Jane Smith)
 * Romana (BFA: The Apocalypse Element, et al)
 * Rose Tyler (DW: The Stolen Earth/Journey's End, The End of Time)
 * Martha Jones (DW: The Sontaran Strategem through The Doctor's Daughter,The Stolen Earth/Journey's End, IDW: Tesseract/Don't Step on the Grass, DW: The End of Time)
 * Jack Harkness (DW: Utopia through Last of the Time Lords, and The Stolen Earth/Journey's End, The End of Time)
 * Mickey Smith (DW: Doomsday, Journey's End, The End of Time)
 * Donna Noble (DW: Partners in Crime (at which point she joined the Doctor), The End of Time (though she never encountered the Doctor).
 * Tegan Jovanka (BFA: The Gathering)
 * Harry Sullivan (DW: The Android Invasion).
 * The Brigadier, his disputed status as companion notwithstanding, has reunited with the Doctor on numerous occasions, having met at one time or another virtually all of his incarnations to date.
 * River Song has a notable relationship with the Doctor, rejoining him at many different points in the Doctor's time line but never in the correct order for the Doctor.

Last Names
Despite being regular characters, the writers of the original TV series never saw fit to assign last names to two Earth companions featured on the series -- Vicki and Polly -- and the final classic-series companion, Ace, came and went without her real name ever being revealed. It was left to the writers of spin-off works to fill in these crucial character points. Vicki was named Vicki Pallister in PDA: Byzantium!, Polly became Polly Wright thanks to MA: Invasion of the Cat-People (though some reference sources assign her the name Polly Lopez), and the Virgin New Adventures novel series established that Ace was actually named Dorothy Gale McShane.

These weren't the only single-name companions, of course, but as Adric, Nyssa, Leela, Romana, and others were not from Earth, no additional names were expected.

Physical Alteration
Travelling through time and space is known to alter the biochemistry of humanoid companions (EDA: Alien Bodies, Unnatural History and Interference), although the Doctor has also been known to provide his companions with a special drug to assist in resisting alien infection, etc. (NA: Deceit). While a prisoner of The Pharm, Martha Jones learned that due to her travelling in time and space, her lympocites had been altered, boosting her immune system (TW: Reset). This change would appear to be permanent; Mrs. Wormwood detected an old, but still present, energy field surrounding former companion Sarah Jane Smith, which indicated to her that Smith had travelled through the space-time vortex - this occurred decades after Smith's last confirmed TARDIS voyage (in DW: The Five Doctors). (SJA: Invasion of the Bane) It has not yet been established whether multiple TARDIS trips are required for this alteration, or if this occurs on initial exposure.

Companions are also given the ability to understand almost any language - Earth or alien - thanks to a Time Lord "gift" that the Doctor shares with them (DW: The Masque of Mandragora, The Christmas Invasion); although details are not known for certain, it is believed that this gift may be bestowed upon companions permanently, given the continued ability of some departed companions to continue communicating in and understanding foreign and alien tongues (DW: The Myth Makers, Frontios, Mindwarp, Dragonfire), their ability to understand the local language seems to continue onwards. However, this is not consistently applied -- Rose Tyler, for example, is unable to understand the Sycorax language until the Doctor regains consciousness, suggesting that in some circumstances the Doctor needs to be not only nearby but awake for the translation to take effect. Also, curiously, when the Doctor does recover, not only do Rose and Mickey (who have been in the TARDIS, and so the fact that they hear translated speech is explained), but Harriet Jones and her aide also hear translated speech, despite never being in the TARDIS (although their close proximity to the TARDIS could explain it) (DW: The Christmas Invasion). There have been also occasions where translations do not occur at all, such as when the Doctor met with Judoon soldiers at the Shadow Proclamation and conversed with them in their native tongue. (DW: The Stolen Earth)

Celebrity Companions
Although not companions in the traditional sense, the Doctor has, from time to time, shared adventures with notable figures in history, in which they function as companions. Examples include H. G. Wells (DW: Timelash), Charles Dickens (DW: The Unquiet Dead), William Shakespeare (DW: The Shakespeare Code), and Agatha Christie (DW: The Unicorn and the Wasp). In the case of Christie, the Eighth Doctor once claimed she actually travelled with him at one point (BFA: Terror Firma), which would make her a full companion. As noted above, the Doctor invited Madame de Pompadour of France to travel with him (though whether he intended for her to become an actual companion or if he only planned a brief journey is unknown) but she died before she could take him up on his offer, although she did briefly travel to the future via a portal between her era and that of the spacecraft SS Madame De Pompadour (DW: The Girl in the Fireplace) The Doctor also claimed to have shared adventures with Mary Shelley (BFA: Storm Warning, BFA: The Company of Friends).

Companions of Other Time Lords
Other Time Lords have been known to have companions in their travels. Before his final corruption into the renegade known as the Master, 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 the increasingly erratic Koschei's actions (MA: The Dark Path). In his battle with the newly regenerated Eighth Doctor, the Master 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 as the Master killed the boy, although the Doctor subsequently restored him to life. (DW: Doctor Who)

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

Noel Coward was a close friend and may even have been a travelling companion of the Time Lady known to the Doctor as Iris Wildthyme. (EDA: Mad Dogs and Englishmen)

When she left the Fourth Doctor in E-Space, Romana was accompanied by K-9 Mark II, and K-9 continued to be her companion after she returned to normal space (WC: Shada, et al). After returning to Gallifrey, Romana has shared numerous adventures alongside one of the Doctor's former companions, Leela (BFA: Gallifrey).

Jackson Lake, while believing himself to be the Doctor, had Rosita as his companion, and in fact the real Doctor initially considered himself to be Jackson's companion. (DW: The Next Doctor)

Non Companion Stories
Prior to the 2005 series revival, the only story in which the Doctor did not have a companion from beginning to end (as opposed to gaining a companion during the adventure, or working with a "one-off" companion) was The Deadly Assassin. The 1996 TV movie and the 2006 and 2007 Christmas specials, The Runaway Bride and Voyage of the Damned, featured the Doctor without an ongoing companion, although he worked closely with "one-off" companions (and invited all three to join him in his travels), and these characters (Grace Holloway, Donna Noble and Astrid Peth, respectively) were and are referred to as companions by the BBC and in reference works (though Donna is a special case as she later returned as a full-time companion). Beginning with the 2008 Christmas special, The Next Doctor, and continuing throughout the 2009 specials, the Doctor again worked with "one-off" companions rather than an ongoing partner, one of whom was Wilfred Mott, the grandfather of series 4 companion Donna Noble. Unlike the earlier examples, the Doctor made no attempt at recruiting anyone for full-time companionship, and in Planet of the Dead abruptly refuses a direct request from Christina de Souza to join him. This was also reflected in BBC Audio and BBC Books releases during this period, which on occasion had the Doctor work with one-offs, but also completely on his own, although IDW Publishing chose to have the Tenth Doctor travelling with companions in the post-Planet of the Dead continuity of the Doctor Who Ongoing comic series and Doctor Who Magazine, likewise, gave the Doctor a companion for the later-era comic strip. With series 5, however, the Eleventh Doctor will be traveling with at least one regular companion again.

Unofficial Companions
Aside from unlicensed fan fiction, only one case is known of the Doctor being shown with a companion in a sanctioned, but unofficial context. In 2007, the BBC/HBO series Extras aired The Extra Special Series Finale, a Christmas-themed episode that concluded the award-winning comedy series. The series starred Ricky Gervais as down-on-his-luck actor Andy Millman. In this episode he is shown taking roles in any TV show or movie offered to him -- including Doctor Who. In the resulting scene, David Tennant cameos as the Doctor in a scene in which Millman plays a monster and Claudia Sermbezis appears as an unnamed companion shown dressed in an Royal Navy uniform; this character has no apparent analogy to any other Tenth Doctor companion. As the scene is intended as a spoof, and is set in the "real world", there is no canoncial basis for the Royal Navy character.

Longevity
Although several companions of long-standing have appeared in the series, with Jamie McCrimmon, Sarah Jane Smith and Romana, for example, appearing over multiple seasons, this is actually a rarity. During the course of the series, most companions have only stayed for either one season, part of a season, or portions of consecutive seasons. This began early on, when Carole Ann Ford (Susan Foreman) left the series shortly into its (and her) second year. Caroline John (Liz Shaw) appeared in only one season, while Matthew Waterhouse (Adric) appeared in the last few stories of Tom Baker's final season, and the first few stories of Peter Davison's before leaving. In the 2005-present revival, to date only Billie Piper (Rose Tyler) appeared as a regular in more than one consecutive season, though she later returned for guest appearances, as did Freema Agyeman (Martha Jones) and Catherine Tate (Donna Noble), both of whom were regulars for only one season. Discounting "one-off companions" who appeared in only a single story such as Sara Kingdom and Astrid Peth, the TV companions with the shortest multi-story tenure to date have been Katarina and Adam Mitchell, both of whom appeared in only two storylines (though Katarina appeared in more individual episodes than Adam).