The Doctor

"The Doctor" was the alias adopted by a renegade Time Lord from Gallifrey who journeyed through time and space with various companions in his obsolete, stolen, Type 40 TARDIS.

Though largely a believer in non-violent conflict resolution, he was also, on occasion, a great warrior. Indeed, some civilisations in the universe translated the word doctor as warrior, (DW: A Good Man Goes to War) whilst others saw him as a compassionate benefactor, worthy of their admiration and assistance. (DW: Last of the Time Lords, The Wedding of River Song)

He was, however, indisputably responsible for billions of deaths —many of which arose from his conclusion to the Last Great Time War. (DW: Dalek) He was virtually the only Time Lord survivor of that great conflict with the Daleks, largely because it was he alone who ended it by obliterating both races. (DW: The End of Time)

From the latter years of his first incarnation onward, he had a pronounced affinity for Earth and the human race. After departing Gallifrey, he voluntarily chose to spend time on the planet (DW: An Unearthly Child, BFA: Summer, The Haunting of Thomas Brewster) and even owned property in Kent. (DWM: Fellow Travellers, PDA: Verdigris, NA: Warlock, Warchild, The Dying Days, EDA: Mad Dogs and Englishmen and several others) Even before the destruction of Gallifrey, the Doctor spent much more time on Earth than on his own homeworld.

Name
The Doctor's true name remained unknown to all but a very few individuals, such as Samantha Jones and River Song. (EDA: Vanderdeken's Children, DW: Forest of the Dead) Apparently his real name was not used by the Time Lords, even in the formal setting of legal trials. (DW: The War Games, The Trial of a Time Lord, The End of Time) The title "Doctor" was not undeserved, however, as he did hold a doctorate of some sort (DW: The Armageddon Factor), had formally studied medicine on at least 19th century Earth, (DW: The Moonbase), and frequently displayed detailed medical knowledge. (DW: The Ark, Frontios, The Empty Child, New Earth, The Time of Angels, The Curse of the Black Spot and many others) At least some versions of his sonic screwdriver had the capacity to perform medical scans. (DW: The Empty Child, A Good Man Goes to War)

The Doctor claimed to hold doctorates in at least medicine and cheesemaking (DW: The God Complex). According to Pompeiian soothsayers, his name was written in the stars of the Medusa Cascade. (DW: The Fires of Pompeii) Members of an unidentified race of pan-dimensional beings also knew the Doctor's real name at one point. (BBCR: The Last Voyage). According to the Master, he had assumed the name to reflect his constant need to make other people better. (DW: The Sound of Drums)

In one story, he had taken the moniker after his first contact with humans. Colonists on the medical/penal colony of Iwa began calling him "Doctor" after his arrival. He failed to correct them. After they left the planet, "the Doctor" and "Susan" simply kept the names that they had been given by the humans. (TN: Frayed) River Song believed, however, that the Doctor had influenced the etymology of the noun doctor, and was, in several languages, the original source of the word. (DW: A Good Man Goes to War)


 * For a longer discussion of the mystery of the Doctor's true name and of his other aliases, see Aliases of the Doctor.

Age
The Doctor's age was a matter of great confusion, largely caused by his own statements. Immediately after his sixth regeneration, his seventh self claimed to be 953. (DW: Time and the Rani) The Tenth Doctor later claimed to be only 903. (DW: Voyage of the Damned), and, at least prior to leaving Amy and Rory behind, (DW: The God Complex) the Eleventh Doctor continued to maintain an age less than that of his seventh incarnation. (DW: Flesh and Stone, The Impossible Astronaut)

Romana I once caught him "rounding down" his age (DW: The Ribos Operation) while the Eighth Doctor once flatly admitted that he didn't necessarily use the same definition of the word year each time he gave his age to someone. (BFA: Orbis)
 * A more detailed discussion of this topic is available.

Before the Time War
The Doctor's familial relations were at best unclear. According to one account, the Doctor was one of the forty-five cousins created by the Loom of the House of Lungbarrow on Gallifrey. When the House disowned him, he said he had "other families." (NA: Lungbarrow) However, the Eighth Doctor once let it be understood that he was born to a human mother. (DW: Doctor Who) Later, the Tenth Doctor appeared to be serious when he told Martha Jones he had once had a brother (DW: Smith and Jones) — an impossible relationship if all Time Lords were "Loomed" rather than born biologically.

The Eighth Doctor told Grace Holloway he had a father. (DW: Doctor Who) The Tenth Doctor told Sally Sparrow he had had several weddings, (DW: Blink) and Ood Sigma that one of them was to Elizabeth I. (DW: The End of Time) An earlier incarnation had also been wed, (MA: Cold Fusion) probably to Patience. (PDA: The Infinity Doctors) One brother was Irving Braxiatel (BNA: Tears of the Oracle). The Doctor had more than one child. (DW: Fear Her, The Doctor's Daughter) These children were "sons or daughters, or both." (PDA: The Eleventh Tiger)

He had a granddaughter, Susan Foreman and two other grandchildren, John and Gillian. (TVC: The Klepton Parasites)

At one point, the Doctor became the adoptive father of a female Time Lord named Miranda Dawkins, whom his eighth incarnation reared until her mid-teens. (EDA: Father Time) Miranda later gave birth to a daughter, Zezanne, and died while trying to protect the Doctor (EDA: Sometime Never...).

The Doctor also had a great-grandson named Alex. Alex was the son of Susan and David Campbell. (BFA: An Earthly Child) He went on several adventures with the Eighth Doctor and even backpacked around the Earth with Lucie Miller. (BFA: Lucie Miller') Susan and David also had adopted children, Barbara, Ian and David (EDA: Legacy of the Daleks'') —meaning that the Doctor was an adoptive great-grandfather as well as a biological one. ''

All of these family members were believed lost to the Ninth Doctor, along with the rest of his race. (DW: Dalek) Most were likely exterminated at his own hand at the conclusion of the Last Great Time War, though some had died, or at least gone missing, before it. (DW: The Tomb of the Cybermen, The Curse of Fenric; BFA: To the Death)

After the Time War
Genetic material from the Doctor in his tenth incarnation was used to create a daughter, Jenny. Although initially spurning her, he soon considered Jenny his daughter and invited her to travel with him in the TARDIS. Before she could join him, however, she was shot. The Doctor believed Jenny to have died, although unknown to him, she underwent a partial regeneration after his departure and survived, at which point she set out on her own life of adventure. (DW: The Doctor's Daughter)

When the Earth was relocated to the Medusa Cascade, a clone of the Doctor was created; this clone later was exiled by the Doctor to Pete's World. Technically, the clone can be considered a relative of the Doctor's. Also, Sarah Jane Smith referred to the Doctor's companions as his family saying "you act like such a lonely man, but you've got the biggest family on Earth!" (DW: Journey's End)

The Eleventh Doctor married River Song, making Amy Pond and Rory Williams his mother and father in-law. (DW: The Wedding of River Song)

Marriages
During an encounter with Ood Sigma, the Tenth Doctor claimed to have married 'Good Queen Bess', or Elizabeth I, a decision that didn't end well and led to her declaring him an enemy (DW: The Shakespeare Code, The End of Time, The Beast Below). This does not appear to be the Doctor's only marriage, as he remarked to Sally Sparrow about being "rubbish at weddings, especially my own." (DW: Blink) In his eleventh incarnation, the Doctor accidentally became engaged to Marilyn Monroe, and married her the same night in what he later claimed was not a real chapel. (DW: A Christmas Carol)

It was hinted throughout the appearances of River Song that she and the Doctor had a physical relationship somewhere in her past and his future relative to the Eleventh Doctor's encounter with the Silence in Florida. (DW: Silence in the Library / Forest of the Dead, The Time of Angels / Flesh and Stone, The Pandorica Opens / The Big Bang, Day of the Moon)

A Tesselecta version of him married her in an alternate timeline shortly before his "death". He subsequently spoke as if he considered them husband and wife. (DW: The Wedding of River Song)

Languages
The Doctor spoke five billion languages, (DW: The Parting of the Ways), though he was likely assisted by the TARDIS' telepathic translation circuits. His native language was probably Modern Gallifreyan, but he seemed to prefer speaking British English, (DW: The Mind Robber) always with an accent that on Earth was similar to accents used in the British Isles. (DW: An Unearthly Child, The Power of the Daleks, Spearhead from Space, Robot, Castrovalva, et al.) This accent changed from incarnation to incarnation. For example, the Doctor's seventh incarnation spoke with an accent similar to one used in Scotland (DW: Time and the Rani) Both Rose Tyler and Harriet Jones noted the accent of his ninth self sounded like it came from "the north" or was "a northern accent", referring to the north of England. (DW: Rose, World War Three) American Grace Holloway once told a San Franciscan policeman that the Eighth Doctor was "English". (DW: Doctor Who)

He could read and write Old High Gallifreyan, (DW: The Time of Angels) an unusual skill even among Time Lords. (DW: The Five Doctors) He spoke the language of the Judoon (DW: The Stolen Earth), Delphon (a language "spoken" using only eyebrow movements) (DW: Spearhead from Space), several Chinese languages (DW: The Mind of Evil, The Talons of Weng-Chiang), Ancient Martian (DW: The Waters of Mars), Tritovore (DW: Planet of the Dead) and either Celtic or Welsh (DW: The Fires of Pompeii) and knew at least some Sycoraxic. (DW: The Christmas Invasion) He did not seem to understand French in his second incarnation (DW: The War Games), but later became fluent in it across several periods of French history. (DW: The Girl in the Fireplace) He also spoke "baby" (DW: A Good Man Goes to War, Closing Time) and "cat". (DW: The Lodger)

Connections with Earth
Although the Doctor visited many worlds, the planet Earth was the one for which he had the closest affinity. He displayed immense knowledge of and interest in Earth history. He was either an observer of or an active participant in countless major events in its history. (DW: Marco Polo, The Dalek Invasion of Earth, The Crusade, The Romans, The Time Meddler, et al.) As noted earlier, he found himself exiled to Earth during his third incarnation, very much against his wishes. In this time he worked with UNIT and later was a good friend to former colleagues such as Brigadier Lethbridge-Stewart, Sergeant Benton, Mike Yates, Liz Shaw, Jo Grant, Sarah Jane Smith and Harry Sullivan. (DW: Spearhead from Space, Terror of the Autons, The Ark in Space)

He seemed to particularly like Great Britain. When Angus Goodman asked him if he was British, he replied he wasn't, but thanked Gus for the compliment. (DWM: 4-Dimensional Vistas) He considered himself British soon after his regeneration into his eighth incarnation. (DW: Doctor Who) Toward the end of his tenth incarnation, when asked if he "was British or something", the Doctor responded that he was "something". (DW: Dreamland)

His incarnations spoke in accents based upon different regions of the United Kingdom, most notably his seventh incarnation (who had a Scottish accent) and his ninth, whose accent resembled that of the north of England - though he tried to pass it off by claiming "lots of planets have a North!" (DW: Rose) His tenth incarnation once adopted a convincing Scottish accent as part of a disguise, (DW: Tooth and Claw) though he was also known to briefly adopt an American one (DW: The Christmas Invasion, Dreamland)

The vast majority of the Doctor's known companions were humans hailing from various points in the planet's history, with a strong bias towards the 20th and 21st centuries. (DW: An Unearthly Child, The Massacre of St Bartholomew's Eve, The War Machines, The Wheel in Space, Rose, Dalek, School Reunion, et al.) His ninth and tenth incarnations developed a network of friends and former companions at one point referred to as the Doctor's Secret Army or the Children of Time. Thanks to their knowledge of him, they were able to summon him at a time of desperate need when he was unable to find Earth. This allowed him to arrive to save the day with his companion of the moment, Donna Noble. This threat, Davros' New Dalek Empire required the combined power of the Doctor and all of the companions and friends of his Secret Army to defeat. Among them were Sarah Jane Smith, (who referred to his companions as his family) her computer Mr Smith, her robotic dog K9 and her son Luke Smith; Captain Jack Harkness and his Torchwood team; Harriet Jones (who sacrificed herself to help summon him); Donna Noble, her mother and grandfather who helped summon the Doctor; Martha Jones who was given a job at UNIT after she left the Doctor; Mickey Smith, who had briefly travelled with him; Rose Tyler and her mother Jackie who showed up to help from Pete's World (the parallel world they were living on). Also, a clone of the Doctor was created that played a role in this crisis, but was left behind on Pete's World with Rose to live out a normal, human life. (DW: School Reunion, Rise of the Cybermen / The Age of Steel, Doomsday, The Stolen Earth / Journey's End, TW: Reset)

The general populace of Earth remained oblivious to the Doctor's ongoing efforts to protect the planet, and unaware of his existence. There were exceptions to this, however. During the Sycorax invasion, Prime Minister Harriet Jones made a public appeal over the UK airwaves for the Doctor to intervene. (DW: The Christmas Invasion) The Tenth Doctor appeared on international television to light the Olympic flame at the 2012 London Games, though he was never identified. (DW: Fear Her) By the early 21st century, the Doctor had also become something of a cult figure, with at least one group, LINDA, following his exploits (DW: Love & Monsters, Time Crash), and conspiracy theorists dedicating websites to solving the "Who is the Doctor?" mystery (DW: Rose, World War Three, et al). At some time after 2059, due to the Doctor altering history, a media website ran a story about "The Mythical Doctor" and his involvement in the Bowie Base One incident on Mars and his rescue of two of its crewmembers. (DW: The Waters of Mars)

Perhaps the widest knowledge of the Doctor came during the The Year That Never Was, when Martha Jones travelled around Earth, spreading tales of the Doctor and generating a groundswell of faith in him that facilitated the defeat of the Master; this timeline, however, was ultimately negated and forgotten by all but a few individuals. (DW: Last of the Time Lords)

The Doctor established friendships with many well-known humans throughout history, including: William Shakespeare, for whom he transcribed the first folio of Hamlet (DW: City of Death) and shared an adventure (DW: The Shakespeare Code); Winston Churchill (DW: Victory of the Daleks), Frank Sinatra (DW: A Christmas Carol); Vincent Van Gogh (DW: Vincent and the Doctor); Mary Shelley (BFA: The Company of Friends); Sir Isaac Newton (DW: The Pirate Planet). He was married to Marilyn Monroe and claimed to know the real Santa Claus. (DW: A Christmas Carol)

Influence
The Doctor belonged to the Prydonian Chapter, the most important chapter of Time Lord society. (DW: The Deadly Assassin) He had a profound influence on many worlds and was written into their histories (DW: Forest of the Dead); as a result, he has been the recipient of many honours including being made a noble of Draconia (DW: Frontier in Space) and a knight of the British Empire. (DW: Tooth and Claw)

Having broken the Time Lords' non-interference policy, in his second incarnation he was put on trial as a renegade. (DW: The War Games) Subsequently, for a time, he acted as agent of the Time Lords' Celestial Intervention Agency before the beginning of his sentence on 20th century Earth. (PDA: Players, World Game) Following his defeat of Omega, which saved Gallifrey, he was granted a pardon and given his freedom. (DW: The Three Doctors)

In his fourth incarnation, as part of a ploy to outwit invaders of Gallifrey, he was a candidate for the position of Lord President of the High Council. (DW: The Invasion of Time) In his fifth incarnation, he was put on trial again for recklessness. (DWM: The Stockbridge Horror) He was later given the title of Lord President by Councillor Flavia, against his wishes. He pretended to accept the office but ran away in his TARDIS. (DW: The Five Doctors) Prior to the Doctor's trial during his sixth incarnation, he was deposed in absentia and put on trial for breaking the non-interference policy and, later in the same trial, for genocide,. The validity of the trial was called into question when it was discovered that it had been orchestrated by an evil future manifestation of the Doctor, the Valeyard, and mooted. (DW: The Trial of a Time Lord)

Biographical summary

 * For more detailed biographical information see articles for individual incarnations. For information on the Doctor's earliest life, see First Doctor.

The Doctor left Gallifrey and became a hero who fought evil and injustice across the universe in violation of the Time Lords' non-interference policy. (DW: The War Games) Technically, he explored only with the intention of experiencing the wonders of the universe and having fun, but frequently became embroiled in machinations and crises that ended with him defeating the foe and saving the planet he was visiting. He travelled with many companions, beginning with his granddaughter, Susan Foreman, who also came from Gallifrey. (DW: An Unearthly Child, The Sensorites, Gridlock)

Eventually, he was called to account for his crimes against the Time Lords during his second incarnation. His punishment was a forced regeneration and exile to Earth, as well as the loss of his knowledge of how to control the TARDIS. (DW: The War Games) This knowledge was restored to him after he helped to defeat Omega. (DW: The Three Doctors)

The Doctor fought in the Last Great Time War between the Time Lords and the Daleks. He was ultimately responsible for ending the war, likely with the action which resulted in the obliteration of Gallifrey, as well as the supposed extinction of both races, apart from the Doctor himself. (DW: Dalek) The Doctor defeated the Time Lords by sealing them in a Time Lock (IDW: Don't Step on the Grass). They escaped with the help of the Master, but the Doctor re-imprisoned them, along with the Master, within the Time Lock. (DW: The End of Time)
 * For details on the Last Great Time War and its survivors, see the separate article.

The Doctor's incarnations
Through the power of regeneration, the Doctor's personality and outer form greatly changed over time, although all his incarnations were essentially the same person. He continued to be a heroic figure, fighting the evils of the universe wherever he found them, even if his values and motives were often alien to humankind. So far, the Doctor is known to have had eleven incarnations: (DW: The Tenth Planet, The Power of the Daleks, The Five Doctors, The End of Time)
 * The First Doctor was an unreadable, guarded figure. This Doctor was often irascible. He was protective of young women who reminded him of his granddaughter, Susan. He was a brilliant, often short-tempered scientist and keen strategist.
 * The Second Doctor, in contrast to his preceding incarnation, was warm and wise. He was as surprised and frightened of alien menaces as those who faced them with him. He had a knack for manipulation and deception. He loved tootling on his recorder, and carried around a 500-year diary. He wore a big fur coat that dwarfed him, tying it closed with twine. He initially also wore a strange hat, but soon discarded it.
 * The Third Doctor was more of a dashing figure than his predecessors, described by his first incarnation as a "dandy". (DW: The Three Doctors) He had a penchant for inventing gadgets and was skilled at martial arts, particularly Venusian aikido. His initially difficult relationship with the Brigadier softened to an easy, mutual trust during his exile on Earth. His also displayed great affection for his female companions, particularly Jo Grant and Sarah Jane Smith.
 * The Fourth Doctor was more eccentric than his previous incarnations, and was the first incarnation to appear "young". Rarely without his very long scarf, he travelled with several individuals. He always carried jelly babies in his pockets, using them as bluffs, gifts and distractions - and occasionally snacks. (DW: Robot, The Face of Evil, The Invisible Enemy, The Ribos Operation, Full Circle, Logopolis) Although he retained his fondness for earth (DW: The Stones of Blood), he ended his regular association with UNIT almost immediately upon his regeneration and only occasionally returned to the planet.
 * The Fifth Doctor was fond of cricket and wearing a stick of celery on his lapel. This energetic, compassionate Doctor was nervous after a difficult regeneration, but like his previous incarnations, when he found himself in a corner, used improvisation as the best way out. He occasionally wore glasses, even though he didn't need them (DW: Time Crash).
 * The Sixth Doctor was a grandiose and eloquent incarnation. He sported a parti-coloured wardrobe that looked as if it were designed by Christian Lacroix, often commented upon. His manic personality and acerbic wit could shade into moral passion. (DW: The Twin Dilemma, Attack of the Cybermen) He was also capable of violent action, more so than his predecessors (DW: The Twin Dilemma, The Two Doctors).
 * The Seventh Doctor had a voice touched by a Scottish burr. A keen strategist, scientist and, especially early in his incarnation, light hearted, this incarnation was a plotter of the highest order. Embracing the complexities of time travel and his ability to manipulate and plan for the future, he fully embraced his role of Time Lord, even if it meant risking alienating his companion (DW: The Curse of Fenric).
 * The Eighth Doctor showed a romantic and sensitive side not displayed by previous Doctors. More morally flexible than his immediate predecessor, the Eighth Doctor suffered from bouts of amnesia, first after his regeneration and again after the first destruction of Gallifrey, following the War with the Enemy. Unlike other Doctors, the Eighth spent his travels crossing between parallel universes and amidst time paradoxes.
 * The Ninth Doctor was a survivor of the Last Great Time War. He displayed much of the playfulness of his previous incarnations, but was emotionally and psychologically scarred by War and his role in it, which sometimes resulted in a detachment that was interpreted by some as being cruel. (DW: The End of the World, Dalek)
 * The Tenth Doctor had a manic personality. He had a fondness for human pop culture reference. However, memories of the Time War were still something he lived with. While he had a bright, playful side, he was frequently ruthless. (DW: The Christmas Invasion, Tooth and Claw, School Reunion) He also had a romantic side that resulted in him falling in love with one companion, though he was unable to express this himself (DW: Journey's End, et al) and experiencing romance on occasion, including with historic figures Madame de Pompadour (DW: The Girl in the Fireplace) and Queen Elizabeth I (DW: The End of Time).
 * The Eleventh Doctor was smug about his abilities and exhibited a renewed youthful enthusiasm for adventure. He had keen observational skills, an obsession with seeming trivia and a calm personality which would quickly turn frantically angry and ruthless when events demanded. (DW: The Eleventh Hour, The Beast Below) He frequently referred to himself as being old, showing his age on more than a few occasions (DW: The Big Bang, The Impossible Astronaut)

An interesting aspect of the Doctor's personality was that he occasionally expressed a personal liking for particular incarnations, though this opinion depended on the incarnation making the assessment. The Doctor's tenth incarnation expressed a deep fondness for his fifth incarnation (DW: Time Crash). The Fifth Doctor was disliked by his immediate successor (DW: The Twin Dilemma), though this may have been due to his particularly traumatic regeneration. In another instance, the fourth made reference to the third, saying "Some people liked it, but I prefer this one" (DW: The Brain of Morbius). Immediately before his tenth regeneration, the Tenth Doctor stated, "I don't want to go". Immediately after his tenth regeneration, the Eleventh Doctor remarked upon his new nose, stating that "I've had worse" - probably a reference to his third incarnation, who was once described as a "long-shanked fellow with a mighty nose". (DW: The End of Time, The Time Warrior)

Regeneration
Due to the unique structure of Time Lord biology the Doctor had the ability to regenerate, to "cheat death". (DW: The Parting of the Ways)

A Time Lord was usually limited to twelve regenerations, making the "thirteenth Doctor" the last. (DW: The Deadly Assassin, Doctor Who) Later, however, the Eleventh Doctor stated that he could change his appearance five hundred seven times. (SJA: Death of the Doctor) It is unknown if this is something which had changed or if the Doctor was simply being sarcastic. The High Council of the Time Lords could influence regenerations, treating them as punishment (DW: The War Games) and reward (DW: The Five Doctors, Utopia). At least twice, enemies coveted the Doctor's future regenerations and tried to take them for their own (Mawdryn in DW: Mawdryn Undead and the Master in the 1996 TV movie).

The Doctor is known to have regenerated ten times, for a total of eleven incarnations. At one point during his life, the Tenth Doctor, following an attack by a Dalek, began to regenerate, but cancelled this by channelling the energy into his severed hand; whether this counted as a full regeneration is unknown, though in his next incarnation the Doctor explicitly considered himself the eleventh (DW: The Lodger).

The exact circumstances surrounding the Doctor's regenerations are known with the exception of his eighth. An event that occurred in one chronicle (DW: The Brain of Morbius) implied the Doctor may have had more incarnations, but during a later incident during the Doctor's fifth incarnation, when asked by the First Doctor what regeneration he was up to, the Fifth Doctor answered "Fourth," leading his first incarnation to exclaim, "Good heavens, so there are five of me now!". (DW: The Five Doctors) As mentioned above, the Eleventh Doctor referred to himself directly as the eleventh on several occasions.

Further confusing the issue, the Eleventh Doctor not only died, but did so while his remaining regenerations were disabled. He was revived by Melody Pond, who used her own remaining regenerations, so it is unclear not only if the Doctor was even capable of further regeneration, but also how many he had left. (DW: Let's Kill Hitler)

The effect of regeneration on the Doctor in the time immediately following the event varied from incarnation to incarnation. In some cases the Doctor regained his faculties quickly, erratic behaviour notwithstanding. (DW: The Power of the Daleks, The Twin Dilemma, The Eleventh Hour) On one occasion when the regenerative process was postponed for a long time, he was rendered amnesiac. (DW: Doctor Who) In most cases the Doctor was incapacitated for a period of time before ultimately recovering. (DW: Spearhead from Space, Robot, Castrovalva, Time and the Rani, The Christmas Invasion) There was also a unique case where the Doctor (through will or the nature of his injury) was able to delay regeneration from setting in for an extended period of time - long enough to visit all of his past companions - though the resulting energy release was catastrophic for the TARDIS (DW: The End of Time; SJA: Death of the Doctor).

Although it was considered a major violation of the Laws of Time, on several occasions different incarnations of the Doctor met and interacted, sometimes with Time Lord High Council sanction, (DW: The Three Doctors, The Five Doctors, The Two Doctors) and sometimes accidentally. (DW: Time Crash) In the last case, the only known occasion of incarnations meeting following the fall of Gallifrey in the Last Great Time War, it would appear that, without Time Lord interference, a major disruption in time and space could be caused by such meetings. (DW: Father's Day, Time Crash)

Causes
Details were known only about the cause of ten of the Doctor's full regenerative cycles, and a couple of "near-misses".


 * First Doctor: Weakened by Mondas as it drained Earth's energy, succumbing to old age. (DW: The Tenth Planet)
 * Second Doctor: Forced upon him by the Time Lords, as part of his punishment for breaking the Laws of Time. (DW: The War Games)
 * Third Doctor: Radiation poisoning from the Great One's web of Metebelis crystals. (DW: Planet of the Spiders)
 * Fourth Doctor: Plummeted from the Pharos Project radio telescope. (DW: Logopolis)
 * Fifth Doctor: Exposure to unrefined Spectrox. (DW: The Caves of Androzani)
 * Sixth Doctor: Injured in the Rani's crash-landing of his TARDIS after being weakened from his battle with the Lamprey. (PDA: Spiral Scratch, DW: Time and the Rani)
 * Seventh Doctor: Caught in crossfire in a gang war, with subsequent heart surgery ending his life. (DW: Doctor Who)
 * Eighth Doctor: Unknown causes, but ostensibly had to do with the Last Great Time War. (IDW: The Forgotten)
 * Ninth Doctor: Removed the Time Vortex's energy from Rose Tyler, channelling it back into the heart of the TARDIS. His brief possession ruined his cellular structure. (DW: The Parting of the Ways)
 * Tenth Doctor: Absorbed the radiation from a vented nuclear bolt supply in order to spare Wilfred Mott from it. (DW: The End of Time)

In addition, the Eleventh Doctor was seen apparently beginning regeneration after being shot by the astronaut just prior to his death (DW: The Impossible Astronaut), but it was later learned this was the Teselecta impersonating him and simulating regeneration with the real, miniaturized, Doctor inside. (DW: The Wedding of River Song)

The Tenth Doctor also had a brush with regeneration. He began, but did not finish, a genuine regenerative cycle after being shot by a Dalek. He used the regeneration to heal himself, but then siphoned off the rest of the cycle into his extra hand. (DW: The Stolen Earth/Journey's End)

"Doctor Who"
The use of the name "Doctor Who" when referring to the Doctor is disapproved of by most fans. Despite this, the ending credits for the series gave his name as "Doctor Who" or "Dr. Who", from 1963 until 1980, when new producer John Nathan-Turner changed this policy, making his name in the end credits "the Doctor". This remained in place through the end of the original series in 1989. Executive Producer Russell T Davies used "Doctor Who" when the series returned in 2005, but Tenth Doctor actor David Tennant asked to change it back to "the Doctor" beginning in 2006. This tradition has continued into the Matt Smith era.

Throughout the franchise's history it has been common for media and cast members to refer to the character as "Dr. Who".

In the series, only one character, WOTAN in 1966's The War Machines, has ever directly referred to him by this name. In the 2005 episode Rose, a website called "Who is Doctor Who?" is introduced, though the name is presented as a question put forward by a conspiracy theorist and no one actually uses the name in dialogue. A line of dialogue written for DW: The Empty Child, but cut, would have had the Doctor himself use the name as part of a joke involving Star Trek (after being hailed as "Mr. Spock" by Rose, the Doctor was to have muttered, "I'd rather be Doctor Who than Star Trek").

Other media, 1960s and early 1970s Doctor Who Annuals, comics and Target Books (most notably the Doctor Who and the Zarbi, not technically a Target Books novelisation, but reprinted by them) have called the Doctor "Doctor Who". Even then, dialogue between characters usually referred to him as "the Doctor".


 * Further in-universe references are considered at the "Doctor Who?" running joke.

Casting
As of 2011, every actor to portray the Doctor has been male, white, and born in the United Kingdom. Despite the fact that the Doctor is not a native of Britain, or of Earth for that matter, every actor to play him so far has had a British accent, much in the way most aliens in the Star Trek franchise tend to speak with an American accent. The type of British accent has varied from one incarnation to the next. The earliest incarnations used RP, whereas more recent incarnations have had Estuary accents. The Ninth Doctor was unique in that he had a Northern accent, causing Rose to ask why an alien would have a Northern accent, to which he replied "Lots of planets have a north." (DW: Rose) In recent years there has been speculation over whether Time Lords might be able to change races or even sexes when regenerating. While the former idea was first postulated by Tom Baker and never taken seriously, during the recent casting for the Eleventh Doctor, at least one black actor (Paterson Joseph) was considered a leading contender ("A Chat with Paterson Joseph" on TV.com). Actors from the United States and Canada, (in one case Australia) have been rumoured as contenders for the role over the years. Actors considered for the role have varied widely in age, from their twenties to sixties. To date the oldest actor to be cast as the Doctor has been William Hartnell, who was 55; the youngest has been Matt Smith, who was 26 when cast. Jon Pertwee was 77 when he made his final official performance as the Doctor in a BBC Radio serial, making him the oldest actor to play the part in an officially licensed capacity. His closest rival is Tom Baker, who turned 77 in 2009, the year he recorded a series of Doctor Who audio dramas. Peter Davison, Colin Baker, Sylvester McCoy and Paul McGann, all in their fifties or sixties, continue to portray the Doctor in licensed audio dramas produced by Big Finish Productions, with McGann also appearing in audio dramas produced by Big Finish for broadcast on BBC7 radio.

Analogous characters

 * See Pastiches of the Doctor