Including the various non-numerical versions like John Hurt's War Doctor, Ncuti Gatwa is the 18th actor to be cast as one of the Doctor's many regenerations, not counting the Timeless Child's fleeting appearances. Each actor has a unique take on the character which defines the show while they're in the role. After his standout performance as Eric Effiong in Sex Education, Gatwa brings plenty to the Doctor Who cast, and because each version of the Doctor is different, will have ample opportunity to put his unique stamp on this iconic and well-storied time traveler.

Related

Why Each Doctor Regenerated In Doctor Who

Doctor Who's titular Time Lord has regenerated many times over the years, but the process has been triggered by a wide array of injuries.

Posts

18 The First Doctor - William Hartnell (1963-1966), Richard Hurndall (1983) & David Bradley (2017-)

Main Run: 134 Episodes, Doctor Who Seasons 1-4

The First Doctor kick-started the entire series in 1963, originally played by William Hartnell. He also remains one of the few regenerations of the Doctor that has traveled with another Time Lord — the Doctor's granddaughter, Susan. William Hartnell played the First Doctor, and his no-nonsense personality and dry wit made him different from the regenerations that came after. Unlike other Doctors, Hartnell's iteration was strikingly stern toward humans, albeit able to exude a warmer side when required. Hartnell's brilliant and commanding presence created the template that all Doctor Who Doctors after him have followed in one way or another.

After William Hartnell left Doctor Who, he made a small appearance in the show's first multi-Doctor story, "The Three Doctors," in 1973, before ing away two years later. The First Doctor was recast for 1983's "The Five Doctors," with Richard Hurndall taking on the role. The First Doctor next appeared in 2017's "Twice Upon A Time," this time played by Harry Potter actor David Bradley, who had previously acted as William Hartnell in Doctor Who biographical drama An Adventure in Space & Time. Bradley's First Doctor reemerged in 2022's "The Power of the Doctor," and could potentially make further appearances as Doctor Who's latest First Doctor.

17 The Second Doctor - Patrick Troughton (1966-1969)

Main Run: 118 Episodes, Doctor Who seasons 4-6

Nothing lasts forever, and Doctor Who is no exception. When William Hartnell had to leave Doctor Who, the Doctor regenerated and changed into Patrick Troughton, the Second Doctor. Troughton originally had an uncredited appearance during the regeneration scene in Hartnell's final episode "The Tenth Planet", with his first credited appearance being in "The Power Of The Daleks". Sadly, however, the episode is now completely missing, having been lost over the decades since its release (although an animated version was released in 2016 by the BBC).

Patrick Troughton's introduction as the Second Doctor was significant not just because it was his first regeneration, but because it introduced the concept of regeneration and the fact there would be multiple versions of the Doctor to the Doctor Who mythos. Aside from the new face, Troughton's Doctor also started the tradition of each version bearing a different personality compared to previous regenerations. The Second Doctor was much more relaxed, clownish, and had a strong sense of humor. Troughton also gave the show a more modern edge, adding a levity that the First Doctor did not possess. The actor returned to Doctor Who for "The Three Doctors," "The Five Doctors," and 1985's "The Two Doctors."

16 The Third Doctor - Jon Pertwee (1970-1974)

Main Run: 128 Episodes, Doctor Who Seasons 7-11

The Third Doctor, John Pertwee, marked a significant turning point for both the character and Doctor Who as a show in more ways than one. Appearing for the first time in color, the Third Doctor kicked his way onto TV screens in 1970. Interestingly too, John Pertwee's Doctor wasn't seen until his first episode, and the actor wasn't present for Patrick Troughton's regeneration sequence when the Second Doctor parted ways from the show. Since it was only the second time the Doctor had regenerated on-screen, leaving the identity of the Third Doctor as a cliffhanger wasn't seen as unusual at the time, though in retrospect it feels unorthodox since the format of modern Doctor Who is to introduce the next incarnation during the same episode the former one departs.

Jon Pertwee's Doctor was not only stylish and elegant, but also something of an expert in martial arts. In another departure from his predecessors, the Third Doctor spent most of his time on Earth after he was exiled by the Time Lords, and worked with the Doctor Who organization UNIT as a scientific advisor. The Third Doctor was also the first to clash with soon-to-be-iconic villain the Master, and made his only Doctor Who comeback — driving Bessie, no less — in "The Five Doctors."

15 The Fourth Doctor - Tom Baker (1974-1981)

Main Run: 172 Episodes, Doctor Who Seasons 12-18

Even in the modern era of Doctor Who, the Fourth Doctor, played by Tom Baker, remains one of the most famous regenerations. Tom Baker played the Doctor for seven seasons, which not only set a new record for longevity in the role, but also gave the audience enough time to know his Doctor intimately. Whereas the Third Doctor would use wit and Venusian aikido to battle his foes, the Fourth Doctor was more eccentric, even offering Jelly Babies to his enemies.

Tom Baker's era marked the first time Doctor Who aired in the USA, and helped the sci-fi institution reach new heights. Although Tom Baker would not return for any multi-Doctor adventures, he did eventually feature as the mysterious Curator in 2013's 50th anniversary special "The Day of the Doctor." The exact nature of the Curator is left deliberately unclear, although it is heavily implied to be some version of the Doctor, whether that be a future regeneration or the Fourth Doctor's bi-generation.

Related

Doctor Who: The 10 Best Fourth Doctor And K9 Stories, Ranked According To IMDb

The Fourth Doctor and K9 develop one of the most memorable companion pairings across many episodes of Doctor Who’s classic series.

Posts

14 The Fifth Doctor - Peter Davison (1982-1984)

Main Run: 69 Episodes, Doctor Who Seasons 19-21

Long before Matt Smith arrived to play the 11th version of the Doctor in Doctor Who, Peter Davison was the youngest actor to play the Doctor. Davison started playing the Fifth Doctor when he was just 29 years old, setting him apart from previous regenerations, although the Fifth Doctor had a personality that seemed almost to be a juxtaposition to his younger appearance. Far from being brash and cavalier like the Fourth Doctor, Peter Davison's iteration was quiet, reserved, and — when combined with his younger face — seemed wise beyond his years.

The Fifth Doctor was different from his predecessors, coming across as notably more quiet and subdued, and preferring to think things through rather than heedlessly throwing himself into danger. Davison was also the first Doctor to regenerate by sacrificing his life to save a companion, preventing Peri's death in Doctor Who season 21 of the original run. Aside from the non-canon "Time Crash" skit alongside son-in-law David Tennant, Peter Davison returned to Doctor Who for "The Power of the Doctor."

13 The Sixth Doctor - Colin Baker (1984-1986)

Main Run: 31 Episodes, Doctor Who Seasons 21-23

The Sixth Doctor's personality was, in many ways, similar to his style of clothing — loud, extravagant, and boisterous. As Doctor Who faced an uncertain future due to leadership changes at the BBC, Baker's Sixth Doctor cut a less forgiving figure than his predecessors. This incarnation was frequently cold toward companions, haughty in attitude, and — initially, at least — difficult to like.

The mixed reception to the Sixth Doctor may have been why Colin Baker had a notably shorter run on the show compared to many of the other classic incarnations of the Doctor, appearing in only 31 episodes. After Colin Baker left Doctor Who, the Sixth Doctor gained more popularity via a series of Doctor Who audio stories, and his characterization has been further improved by appearances in both Doctor Who's "The Power of the Doctor" episode and the Tales of the TARDIS spinoff.

12 The Seventh Doctor - Sylvester McCoy (1987-1989)

Main Run: 42 episodes, Doctor Who Seasons 24-26

Following the mixed responses to Colin Baker's broody take on the Doctor in his sixth incarnation, the show returned with Sylvester McCoy as The Seventh Doctor the following year. The Seventh Doctor, while complicated and full of contradictions, was much more in-keeping with Tom Baker's popular Fourth Doctor, injecting some levity back into the role that many viewers had felt the Fifth and Sixth Doctor's lacked. Notably, Colin Baker refused to reprise his role for the regeneration sequence, so Sylvester McCoy also briefly portrayed an unconscious version of the Sixth Doctor.

The Seventh Doctor represented himself as a funny figure with a keen sense of humor, but at the same time was also brilliantly calculating — something he hid from his enemies, and even from his friends. McCoy returned the Doctor to a more lighthearted and quirky personality, and this offered fans the welcome sanctuary of familiar ground after the more arrogant Sixth Doctor. Sylvester McCoy portrayed the Seventh Doctor for three seasons, and was the last Doctor before Doctor Who was canceled in 1989. McCoy has since returned in both "The Power of the Doctor" and Tales of the TARDIS.

11 The Eighth Doctor - Paul McGann (1996)

Appeared In The 1996 TV Movie

Paul McGann's Eighth Doctor is something of an anomaly among all the different versions of the Doctor in Doctor Who, since he appeared in the 1996 direct-to-TV movie, with Sylvester McCoy also appearing for a final time as the Seventh Doctor for the regeneration sequence. Following Sylvester McCoy's final episode in 1989, Doctor Who was gone for seven years after the BBC canceled the show. It didn't return until 1996 as a feature-length installment, the movie also titled Doctor Who, which meant the half-human Eighth Doctor never got the chance to shine in his own seasons like other Doctors.

More of a romantic figure closer to modern-day regenerations, Paul McGann's iteration appeared only in a TV movie that was supposed to kick-start a TV reboot, but failed to attract the attention needed. Luckily, McGann returned to his role in multiple Doctor Who audio stories and finally reappeared in live-action for 2013 short film The Night of the Doctor. Most recently, the Eighth Doctor featured in Jodie Whittaker regeneration episode "The Power of the Doctor."

Related

Doctor Who Is Still Copying Paul McGann's Biggest Controversy 27 Years Later

Paul McGann stirred great controversy as the Eighth Doctor, but 27 years after the fact, Doctor Who is still following the divisive precedent he set.

Posts

10 The Ninth Doctor - Christopher Eccleston (2005)

Main Run: 13 Episodes, Doctor Who Season 1 (Modern Era)

Much like the Paul McGann's Eight Doctor, The Ninth Doctor, portrayed by Christopher Eccleston, has something of an odd journey compared to many other versions of the character. Just like McGann, Eccleston took up the role during one of the BBC's attempts to revitalize the franchise for a new era following the 1989 cancelation, this time successful. Christopher Eccleston's Ninth Doctor started the renewed Doctor Who, and even though the actor only played the Time Lord for a single season, he still left his mark.

Christopher Eccleston's Ninth Doctor was somewhat cynical and jaded as a consequence of the recent Time War against the Daleks and the enormous losses he suffered. Nevertheless, the Ninth Doctor's friendship with Rose helped him to see the world differently. After dealing with survivor's guilt due to his actions in the war, history repeated itself. Like the Fifth Doctor, the Ninth Doctor sacrificed himself to save his companion. While Eccleston has appeared in Doctor Who audio stories, he has not yet returned to the TV show.

9 The Tenth Doctor - David Tennant (2005-2010)

Main Run: 47 Episodes, Doctor Who Seasons 2-4 (Modern Era)

While Christopher Eccleston's Ninth Doctor would only appear for a single season, his next regeneration would become a fan-favorite whose impact on the show cannot be overstated. Played by David Tennant, the Tenth Doctor remains one of the most popular Doctors in the franchise's long history. Charming and funny, the Tenth Doctor also had a darker side that emerged after he lost Rose, then evolved into the dangerous Time Lord Victorious.

Tennant's Tenth Doctor was never afraid to charge into danger, and always seemed to thrive when facing enemies. This was the Doctor that introduced a new generation of fans to Doctor Who, and his one-liners and human characteristics made him both instantly relatable and quirky. Following the Tenth Doctor's regeneration, Tennant ed his successor, Matt Smith, for 50th anniversary special "The Day of the Doctor."