On 20 March 2004, it was announced that Eccleston was to play the ninth incarnation of the Doctor in the revival of the legendary BBC science fiction television series Doctor Who, which began transmission on 26 March 2005.

On 30 March 2005, the BBC released a statement, ostensibly from Eccleston, saying that he had decided to leave the role after just one series, because he feared becoming typecast. On 4 April, the BBC revealed that Eccleston's "statement" was falsely attributed and released without his consent. The BBC admitted that they had broken an agreement made in January not to disclose publicly that he only intended to do one series. The statement had been made after journalists made queries to the press office.

On 11 June 2005, during a BBC radio interview, when asked if he had enjoyed working on Doctor Who, Eccleston responded by saying, "Mixed, but that's a long story." Eccleston's reasons for leaving the role continue to be debated in Britain's newspapers: on 4 October 2005 Alan Davies told The Daily Telegraph that Eccleston had been "overworked" by the BBC, and had left the role because he was "exhausted". Ten days later, Eccleston told The Daily Mirror this was not true, and expressed some irritation at Davies for his comments.

On 7 November 2008, at the National Theatre to promote his book The Writer's Tale, Russell T Davies said that Eccleston's contract was for a single year because it was uncertain whether the show would continue beyond a single revival series. In retrospect, he says, it has been an enormous success, but at the time there were doubts within the BBC.

Eccleston was voted "Most Popular Actor" at the 2005 National Television Awards for his portrayal of The Doctor.

Eccleston was very touched by the response he received from children for his role as the Ninth Doctor. He said "In all the 20 years I've been acting, I've never enjoyed a response so much as the one I've had from children and I'm carrying that in my heart forever..."

On 10 January 1996, it was announced that Paul McGann would play the eighth incarnation of the Doctor in the Doctor Who television movie. The television movie also starred Eric Roberts, Daphne Ashbrook, and the outgoing Seventh Doctor, Sylvester McCoy. McGann's brother, Mark McGann, also auditioned for the title role.

The Doctor Who television movie was a joint venture between the BBC, Universal Studios and the Fox Broadcasting Network. McGann had signed a contract to appear as the Eighth Doctor in a new Doctor Who series, if Fox or Universal exercised their option. Thus, the television movie was supposed to be a "back door pilot" in that, if it obtained respectable ratings, the new series would continue to be produced. The movie aired on 14 May 1996 in the US and on 27 May 1996 in the UK. Although it earned 9.08 million viewers and was very successful in the UK, ratings were very low in the United States. As a consequence, Fox did not exercise its option to pick up the series and Universal could not find another network who was interested in airing a new Doctor Who series. Thus no new series was produced until 2005, after all the contractual rights had returned to the BBC, and the movie became McGann's only televised appearance as the Eighth Doctor.

Although McGann played the Doctor on television only once, he gave permission for his likeness to be used on the covers of the BBC's Eighth Doctor novels and he has reprised the role of the Eighth Doctor in an extensive series of audio plays by Big Finish Productions.

For nine years, McGann was treated as the "current" Doctor by some fans until Christopher Eccleston assumed the role in 2005. McGann (1996-2005) is tied with Sylvester McCoy (1987-1996) for serving the longest period of time as the "current" Doctor, at nine years each, though McGann actually had the role for 40 days more. The show was not in production for virtually all of this time, however. McGann's single appearance as the Doctor in the television movie makes him the actor with the shortest "screen time" in that role.

McGann's co-star in Withnail, actor Richard E. Grant, also played the Doctor in the 2003 animated webcast Scream of the Shalka.

Rumours abounded that Paul McGann would reprise the role of the eighth Doctor in a new series of television films, alongside the current television series. McGann has denied these rumours on the grounds of not having being asked back to play the part but if he were to be asked would be interested as long as he "didn't have to wear a wig". McGann has appeared again as the eighth Doctor in the BBC Radio 7 series Doctor Who in 2007 and 2008..

He took over the lead role of Doctor Who in 1987 from Colin Baker, and remained until the series was shelved in 1989. He played the Doctor in the 1993 charity special Dimensions in Time, and again in 1996, appearing in a cameo at the beginning of the Doctor Who television movie where he handed the role over to Paul McGann. In his first series, McCoy, a comedy actor, portrayed the character with a degree of clown-like humour, but script editor Andrew Cartmel soon changed that when fans argued that the character (and plots) were becoming increasingly lightweight. The Seventh Doctor developed into a much darker figure than any of his earlier incarnations, manipulating people like chess pieces and always seeming to be playing a deeper game. McCoy generally approved of this, as it allowed him to play more of a dramatic role.

A distinguishing feature of McCoy's performances was his manner of speech. He used his natural slight Scottish accent and rolled his rs. At the start of his tenure he used proverbs and sayings adapted to his own ends (eg. "There's many a slap twixt cup and lap" — Delta and the Bannermen), although this characteristic was phased out during the later, darker series of his tenure. In 1990, readers of Doctor Who Magazine voted McCoy's Doctor "Best Doctor", over perennial favourite Tom Baker.

Baker made his first appearance in Doctor Who as Commander Maxil in the story Arc of Infinity. Baker's performance was described by producer John Nathan-Turner as being "quite arch" and a little sassy. Despite this, Baker's character became one of the few characters to actually shoot the Doctor, then played by Peter Davison.

When Baker was officially cast as Davison's successor, he became the only "Doctor" actor to have appeared in the television series as another character prior to taking on the leading role. When Baker was cast to replace Davison, many fans cited that shooting scene in Arc of Infinity, prompting Baker to say jokingly that he got the part of the Doctor by killing the incumbent. Colin is no relation to Tom Baker, who played the Fourth Doctor in Doctor Who for seven years.

Baker's first appearance as the Doctor occurred at the final minutes of The Caves of Androzani, where he delivered his first few lines. The closing title sequence for episode four featured Baker's face instead of Peter Davison, and credits him as the Doctor before Davison's own credit. This was the first (and, to date, only) time that the new lead received top billing in the final story of an outgoing Doctor. Baker then made his first full story debut the following week in The Twin Dilemma. It was the first time since 1966, and only the second time in the series' history, that a new leading actor's debut story was shown before the conclusion of the previous lead's season.

Baker's era was interrupted by a long 18 month hiatus which was announced in February 1985, mid way through transmission of his first full season. One new Doctor Who story, Slipback, was made on radio during the hiatus. The Controller of BBC One at the time, Michael Grade, criticised Doctor Who, saying that the programme had become overly violent and its storylines farcical during season 22 in 1985. After the 18-month hiatus, the program was brought back for its 23rd season in the Autumn of 1986. Season 23 featured a reduction of episodes produced, and the 14 episode long serial The Trial of a Time Lord was felt by some fans to reflect the fact that the series itself was "on trial" at this time (although the BBC had on many occasions denied that this was the case).

In 1986, Baker told an interviewer, "Tom Baker did it for seven years. ... There's a part of me which likes to have a tilt at records. I would like to think that maybe I'd still be doing it in eight years' time." However, later that year Baker was dismissed from the part at the insistence of BBC management, who wanted to refresh the show. BBC1 Controller Michael Grade was alleged to dislike Baker's performance and BBC Head of Series Jonathan Powell has since said that the BBC were looking for "one last chance saloon, for an actor who would take off with the public". He was removed from the part after starring in only eleven stories and just short of three years in the part, making his tenure as the Doctor the shortest in the series at that point.

Despite Baker's time in the role being punctuated with numerous personal and professional problems (the death of his son Jack shortly after Baker accepted the role, the 18-month hiatus which followed his first full season and finally his high-profile sacking) Baker remains enthusiastic about his time as the Doctor. He is a regular at conventions and fan events and has returned to the role of the 6th Doctor in numerous audio stories and webcasts, the Dimensions In Time charity special, the video game Doctor Who: Destiny of the Doctors (for which he recorded new audio only) and stage play Doctor Who: The Ultimate Adventure.

In recent years, Baker has appeared on a number of DVD releases of his episodes. His turbulent three years on the show are examined in some detail in the documentary Trials and Tribulations, included in the 2008 DVD release of The Trial of a Time Lord.

In 1981, Davison signed a contract to play the Doctor for three years, succeeding Tom Baker (the Fourth Doctor) and, at age 29, is the second youngest actor to assume the lead role. Attracting such a high-profile actor as Davison was as much of a coup for the programme's producers as getting the role was for him, but he did not renew his contract because he feared being typecast. Reportedly, Patrick Troughton (who had played the Second Doctor and whom Davison had watched on the programme as a teenager) had recommended to Davison that he leave the role after three years, and Davison followed his advice. The Fifth Doctor encountered many of the Doctor's best-known adversaries, including the Daleks (in Resurrection of the Daleks) and the Cybermen (in both Earthshock and The Five Doctors). However, Peter Davison has since stated that he also felt too young for the role, and if given the chance at the role now he would have made a better Doctor.

Davison did, in fact, return to play the Fifth Doctor in the 1993 multi-doctor charity special Dimensions in Time and in the 1997 video game Destiny of the Doctors. He continues to reprise the role in a series of audio plays by Big Finish Productions. He returned once again in "Time Crash", a special episode written by Steven Moffat for Children in Need; in the episode, which aired on 16 November 2007, the Fifth Doctor met the Tenth Doctor, played by David Tennant.

In 1974, 40-year-old Baker took on the role of the Doctor in the BBC's Doctor Who from Jon Pertwee. He was cast because of his performance in The Golden Voyage of Sinbad. Baker was working on a construction site at the time. He was dubbed "Boiler Suit Tom" by the media, as he had been supplied for a press conference with some old studio set clothes to replace his modest garments.

As the Doctor, his eccentric dress and speech — particularly his long scarf and jelly babies — made him immediately recognisable. Baker played the Doctor for seven consecutive seasons, the longest-serving actor in the part on-screen. Baker suggested many aspects of the Doctor's personality. The scarf came by accident: James Acheson, the costume designer, had provided more wool than necessary to the knitter, Begonia Pope, who knitted all she was given; Baker suggested he wear the ridiculously long scarf. Tom Baker in his Doctor Who costume during a parade in Sunderland in 1977.

In October, 1980, the BBC announced just before the serial Full Circle that Baker was leaving at the end of the 1981 season. Baker's departure was based partly on his feeling that he could not develop his role further, and partly on the new producer, John Nathan-Turner's, dislike of Baker's portrayal. Baker's last regular appearance as the Doctor was on 21 March 1981 at the conclusion of the story Logopolis.

Baker is often regarded the most popular of the Doctors. In polls by Doctor Who Magazine, Baker has lost the "Best Doctor" category only twice: once to Sylvester McCoy in 1990, and once to David Tennant in 2006.

Baker is not related to Colin Baker, the Sixth Doctor, nor to Bob Baker, the script-writer for many episodes.

Baker's humour is like that of the character he played. When asked how he felt about having a star named after him, Baker quipped, "I'm over the moon!" In a poll published by BBC Homes and Antiques in January 2006, Baker was voted the fourth most eccentric star. He was beaten by Björk, Chris Eubank and David Icke.

In 1969, Pertwee was selected by producer Peter Bryant to take over as the Doctor from Patrick Troughton in the television series Doctor Who. Pertwee had already applied for the role and was surprised to find he had been shortlisted for it. Prior to becoming The Doctor, Pertwee had had relatively little interest in the programme. In a departure from the Doctor's first two incarnations, Pertwee played the character as an active crusader with a penchant for action and fancy clothes, even while the character was exiled on Earth and serving with UNIT. He played the Doctor for five seasons from 1970 to 1974, at the time the longest stint of any of the actors who played the part, surpassing predecessors William Hartnell and Patrick Troughton's three years each in the role. Only his immediate successor, Tom Baker, would play the Doctor for longer (seven years from 1974–1981). In early 1974, Pertwee announced he would step down as the Doctor in order to resume his stage career in The Breadwinner, also citing typecasting in the role as a reason for quitting. His final regular appearance in the series was in the story "Planet of the Spiders"' in June 1974. On 14 April 1971, Pertwee was the subject of Thames Television's This Is Your Life which featured the first television appearance of his son Sean Pertwee, who went on to become an actor.

In 1966, Doctor Who producer Innes Lloyd decided to replace William Hartnell in the series' lead role. The continued survival of the show depended on audiences accepting another actor in the role, especially given the bold decision that the replacement would not be a Hartnell lookalike or soundalike. Lloyd later stated that Hartnell had approved of the choice, saying, "There's only one man in England who can take over, and that's Patrick Troughton". Lloyd chose Troughton because of his extensive and versatile experience as a character actor. After he was cast, Troughton considered various ways to approach the role, to differentiate his portrayal from Hartnell's amiable-yet-tetchy patriarch. Troughton's early thoughts about how he might play the Doctor included a "tough sea captain" and a piratical figure in blackface and a turban. Doctor Who creator Sydney Newman suggested that the Doctor could be a "cosmic hobo" in the mold of Charlie Chaplin, and this was the interpretation eventually chosen.

During his time on the series, Troughton tended to shun publicity and rarely gave interviews. He told one interviewer, "I think acting is magic. If I tell you all about myself it will spoil it". Years later, he told another interviewer that his greatest concern was that too much publicity would limit his opportunities as a character actor after he left the role.

Troughton was popular with both the production team and his co-stars. Producer Lloyd credited Troughton with a "leading actor's temperament. He was a father figure to the whole company and hence could embrace it and sweep it along with him". Troughton also gained a reputation on set as a practical joker.

Regrettably, many of the early episodes in which Troughton appeared were wiped by the BBC. Troughton found Doctor Who's schedule (at this time, 40 to 44 episodes per season) gruelling, and decided to leave the series in 1969, after three years in the role. This decision was also motivated in part by fear of typecasting.

Troughton returned to Doctor Who three times after he originally left the programme, becoming the only former "Doctor" actor to have reprised the role that many times after his original run. The first time was in The Three Doctors, a 1973 serial celebrating the programme's 10th anniversary. Ten years later, Troughton overcame some reluctance to reprise his role and agreed to appear in the 20th anniversary special The Five Doctors at the request of series producer John Nathan-Turner. He also agreed to attend Doctor Who conventions including the show's 20th Anniversary celebrations at Longleat in 1983. He also appeared around the world with Nathan-Turner. Troughton enjoyed the return to the programme so much that he readily agreed to appear one more time as the Second Doctor with Colin Baker's Sixth Doctor in The Two Doctors (1985). Reportedly, he also advised a later Doctor actor, Peter Davison, to limit his time in the role to three seasons to avoid being typecast and the young actor followed that advice.

Hartnell's performance in This Sporting Life was noted by Verity Lambert, the producer who was setting up a new science–fiction television series for the BBC, Doctor Who. Lambert offered Hartnell the title role. Although he was initially uncertain, Lambert and director Waris Hussein convinced him to take the part and it became the character for which he gained the highest profile and is now most widely remembered. Hartnell later revealed he took the role as it led him away from the gruff, military roles in which he was becoming increasingly typecast, and came to particularly relish the attention and affection that playing the character had brought him from children.

Doctor Who earned Hartnell a regular salary of £315 per episode by 1966 (equivalent to £4,050.90 in modern currency). In comparison, his co–stars Anneke Wills and Michael Craze earned £68 and £52 per episode at the same time. Throughout his tenure as the Doctor, William Hartnell wore a wig and very few photographs exist of him dressed as the Doctor without the wig.

Hartnell suffered a bereavement in 1965 whilst working on The Myth Makers: his aunt, Bessie Hartnell, who had looked after him during his troubled childhood, died. The tight production schedules prevented him from taking time off to attend her funeral.

According to some colleagues on Doctor Who, he could be a difficult person to work with, although others, notably actors Peter Purves and William Russell, and producer Verity Lambert, speak glowingly of him after more than forty years. Among the more caustic accounts, Nicholas Courtney, in his audio memoirs, recalled that during the filming of The Daleks' Master Plan, Hartnell pointed out to him that an extra on the set was Jewish, Courtney's inference being that Hartnell was an antisemite. In an interview in 2008, Courtney claimed that Hartnell "was quite nationalist-minded, a bit intolerant of other races, I think." Hartnell's poor health (arteriosclerosis) as well as poor relations with the new production team on the series following the departure of Lambert, ultimately led him to leave Doctor Who in 1966.

When Hartnell left Doctor Who in 1966, producers of the show came up with a unique idea. Since the Doctor is a Time Lord, he can transform into another man when he dies. Hartnell himself suggested that Patrick Troughton replace him as the Doctor. In Episode 4 of "The Tenth Planet," The First Doctor dies and transforms into the Second Doctor (Patrick Troughton.)

Some commentators now contend that reports of Hartnell's illness were subsequently exaggerated by Lambert's successors in the role of producer, John Wiles and Innes Lloyd, to justify a desire (ultimately successful) to remove the expensive actor from the series. Others suggest that it was a mutual decision between Hartnell and the production team that he should leave the programme. However, Hartnell claimed in later life that he did not want to leave the series, writing, in an oft-quoted letter, "I didn't willingly give up the part". Suggestions that Hartnell's health was not as poor as claimed are seemingly supported by his return to demanding theatre work almost immediately upon leaving Doctor Who. He also made television guest appearances across the late 1960s including in No Hiding Place. According to his granddaughter Jessica Carney's published biography he also made one final film apperance in The Abominable Dr. Phibes (1971) playing the role of a photographer although he is not credited in the end titles of the film.