The Nth Doctor

Everything About Fiction You Never Wanted to Know.
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"Splendid fellows... all of you!"

Some element of a show's Applied Phlebotinum causes a character's appearance and voice to change completely. On Speculative Fiction shows, this can be almost anything. On real-world shows, this is almost always Magic Plastic Surgery - which, on TV, works much better than it does in reality.

This is a catch-all for the recasting of a character using an in-continuity explanation. It takes its name from Doctor Who, whose eponymous Doctor is an alien capable of "regenerating" into a new form whenever he is mortally wounded. This trope, both in the original show and others which employ it, has two benefits; not only can it increase the series' run, it is also a wonderful way to derive drama(with the added bonus of implying that Anyone Can Die, without having to lose major characters).

Compare to: Suspiciously Similar Substitute (which introduces a totally new character much like the old one), The Other Darrin (where the actor is replaced without an in-universe explanation), and Legacy Character (which introduces a different character to the "title" of the previous character).

Examples of The Nth Doctor include:

Anime and Manga

  • Noah in Soul Eater is an artificial construct created by the Table of Contents from the Book of Eibon. The first was Greed and later replaced by Wrath.


  • Rogue Assassin had the whole point of the mystery of the eponymous Assassin having plastic surgery to remain unknown. We don't actually see any of the eponymous Assassin's face and instead the one we THINK is the Assassin was actually his last target who took over his identity.
  • The Matrix Revolutions: Mary Alice replaced Gloria Foster as The Oracle because the character's appearance had changed due to The Merovingian being given her "termination code". In reality, this was an ad hoc handwave made up by the writers because Gloria Foster had died.
  • Heath Ledger's death was dealt with in his unfinished movie The Imaginarium of Doctor Parnassus this way. Johnny Depp, Jude Law, and Colin Farrell played his character in different dimensions.
  • Parodied in the animated film Bolt. When Penny decides to quit being an actor, the TV show she works for replaces her and explains her change in appearance as the result of reconstructive plastic surgery.
  • Parodied in the 2008 Get Smart movie. Agent 99 is shown to have undertaken extensive plastic surgery after her cover was blown. She used to look like a 40 year old blond woman. Now, she's Anne Hathaway.
  • Terry O'Quinn declined reprising the role as the eponymous Ax Crazy in Stepfather III and was replaced Robert Wightman; the change in appearance is dealt with via a Squicky backalley plastic surgery scene at the beginning of the film.
  • Arsenic and Old Lace features a clever parody of this: Jonathan Brewster has had Magic Plastic Surgery from his crazy doctor companion several times, but he only appears with one face (and one actor) in the movie.
    • This coincides a bit with both Absent Actor and Executive Meddling, as the whole gag of the character was that his Magic Plastic Surgeon accidentally gave him the exact likeness of Boris Karloff... who played him in the Broadway production. As the production was still making money at the time the film was set to be produced, the stage producers wouldn't allow Karloff out of his contract long enough to shoot The Movie, and so the film production had to make do with a heavily-made-up Raymond Massey.
  • Blofeld, arch-nemesis of James Bond, is a villainous example. He was played by several actors over the years, with his changes of appearance being explained by plastic surgery. Somewhat justified in that if anyone has the money to be able to employ a magic plastic surgeon it's Blofeld.
    • Bond himself is generally not thought of as an example since the films don't explain his change in appearance. However, in the first movie where Bond's actor changed, the film begins with Bond being rejected by a woman. He then remarks "this never happened to the other fellow!" Some fans have taken this as evidence for the theory that "James Bond" is an alias passed from one 007 agent to the next, a popular theory among fans of the series.
    • The producers of On Her Majesty's Secret Service did briefly consider the plastic surgery idea for Bond, but (wisely for the long run) dropped the idea.
  • The Gemini Killer in The Exorcist III. When he's seen from the main character's perspective, he's played by Jason Miller; when he's seen through what he calls the "eyes of faith", he's played by Brad Dourif.
  • Jobe Smith was played by Jeff Fahey in The Lawnmower Man and Matt Frewer in Lawnmower Man 2: Beyond Cyberspace. The clever rationale is that the explosion at the end of the first film badly burned him, and so he looked different after his face was reconstructed using skin grafts.
    • Less clever when, in the ending of the original film, Pierce Brosnan's character discovered that Jobe had completely uploaded himself into the mainframe, leaving only his skin behind in the real world.

Live-Action TV

  • The Trope Namer is the Doctor in Doctor Who, as mentioned above. Each new regeneration brought with it a new characterization, costume, and personality. But, significantly, all memories and experiences of the past incarnations are maintained, along with a certain amount of character stability (he's always going to be quirky and altruistic and fight evil aliens), meaning the Eleventh Doctor is the exact same person as the First Doctor. Personality is a combination of "nature" and "nurture" - one story said that "Although the aspects of their personality caused by "nurture" would not change, the "nature" contribution to their personality would."
    • The Doctor isn't the only Time Lord to get this treatment; The Master has had a number of onscreen incarnations, and Romana regenerated from Mary Tamm into Lalla Ward -- who, confusingly enough, had appeared alongside Tamm in a serial just before she took over the role. This got explained by Romana liking Princess Astra's appearance so much she decided to regenerate into a double of her.
    • Borusa, a Time Lord on Gallifrey, was in a different regeneration (a different actor) in each of the four stories he appeared in.
    • This trope was also spoofed wonderfully in the unofficial 1999 Doctor Who comedy special "The Curse of Fatal Death," where the Doctor regenerates 4 times throughout the half-hour special. Particularly one moment where the Doctor uses up three bodies in less than a minute (including Hugh Grant's) all because he forgot to unplug a rather large deathray.
    • Though he's been shown to explicitly regenerate only once onscreen (two other times, he's just stolen bodies of other people), seven people have played the Master so far—Roger Delgado, Peter Pratt, Geoffrey Beevers, Anthony Ainley, Eric Roberts, Sir Derek Jacobi and John Simm. (Pratt and Beevers played the same regeneration in two different stories, making the Master a rare case of a character to have been both Nth Doctor and Other Darrin. This was made possible by heavy make-up, as in those two stories the Master was supposedly close to the end of his final life and had degenerated into a visibly decaying near-zombie).
    • A temporary case of this trope occurred in The Mind Robber. Fraser Hines got chicken-pox and had to be replaced for one episode by Hamish Wilson. Fortunately, that serial is something of a Mind Screw, so they were able to provide a "sensible" explanation: Jamie is reduced to a "puzzle" that the Doctor must solve by picking the right facial features. He does so incorrectly and gives Jamie the wrong face. Later on it happens again, and he is able to fix his mistake. Makes about as much sense as anything else that happens in that story.
      • Parodied in a sketch on End of Part One, where the Doctor gets zapped by a death ray, and reveals that it has gone straight through the copy of his contract that was in his jacket pocket. He then regenerates into a bug-eyed Tom Baker lookalike.
    • Yet another Time-Lord (or a part-Time-Lord, at least) has been shown to have the ability- even though- the mysterious River Song aka Mels aka Melody Pond, daughter of Amy and Rory. This example of regeneration is particularly interesting for a number of reasons. 1) It's the first time that we meet a Time Lord's regenerations out of order (we begin with seeing River Song, then we see her first body as a child, and then that body as a baby, and then her third(?) body from childhood to being a young adult. 2) She proved that regenerations can be willingly transferred, so by the time of Forest Of The Dead her (presumably) fourth body was already decidedly her final one. That and Handy also mess with keeping score, so we don't even know how many bodies the Doctor has left.
    • K9's voice actor changed in season seventeen from John Leeson, the person most associated with the role (he's still voicing K9 to this day), to David Brierley. This was explained on-screen by K9 having "robot laryngitis" during the first story of season seventeen (and thus not having to speak or take part) and the Doctor not quite repairing him correctly until the next season.
  • On Sliders, Quinn Mallory's replacement by his non-identical counterpart from another universe, when Jerry O'Connell left the show, is half this and half Suspiciously Similar Substitute.
    • On the other hand, third-season Big Bad Rickman is replaced by a new actor after his first appearance, and this is explained as a side-effect of his vampiric medical condition: in his first appearance, his facial features change momentarily whenever he injects brain tissue from his victims. This transformation turns out to have a small but cumulative permanent effect as well. In reality, Roger Daltrey was simply too expensive to keep on as a recurring character.
  • On Mystery Science Theater 3000: Replacement of voice actors/puppeteers for the robots, as in most puppetry and animation, was usually unexplained. However, the difference in Tom Servo's voice from one actor to another was so severe, that it was given an on-screen nod as Joel replaced Servo's voice module. Similarly, in the eighth season Crow T. Robot was the only one who'd stayed on the satellite for five-hundred-odd years, and thus had gone slightly mad; any other vocal differences were given a Hand Wave in the tenth season when Joel (appearing as The Cameo) suggested that Crow had replaced the bowling pin that formed his mouth.
    • This was also lampshaded in episode 905, where Mike cut himself on Crow, becoming a Were-Crow. In giving Mike the rundown of what being Crow would entail, Crow mentioned that "your voice is gonna change inexplicably every seven years or so."
      • This was also joked about in an interview with Bill Corbett where he explained his initial lack of puppetry skills (as compared to Trace Beaulieu) by stating that "Crow had a stroke."
  • Star Trek: Deep Space Nine replaced Terry Farrell as Jadzia Dax with Nicole de Boer as Ezri Dax. It was already a well-established part of the show's Canon that the character of "Dax" was a symbiote that attached itself to a new humanoid host, thus explaining the new face and somewhat-different personality.
    • This replacement is also a partial Suspiciously Similar Substitute, since the show established that while the symbiote carried its memories from host to host, the hosts themselves were distinct individuals with their own personalities.
    • Interestingly, the episode "The Host" from Star Trek: The Next Generation plays this trope completely straight with regard to the Trill symbiotes; however, as a result it contradicts greatly with Deep Space Nine‍'‍s portrayal.
    • The Borg Queen's hard to tell. She appears to be destroyed in almost every appearance - even by way of retcon, revealing herself to have been on the cube in The Best Of Both Worlds. Yes, her debut is an Unexplained Recovery. She's indicated and proven repeatedly that physical death is a minor inconvenience to her, and it's easy to imagine that her data just goes elsewhere when one body's in mortal danger, though that's not said outright. Coincidentally or not, she's sometimes Alice Krige and sometimes Susanna Thompson, and with so much make-up it's hard to tell who is who.
  • In Smallville, the recurring character Morgan Edge is initially played by Rutger Hauer, and after a near-fatal accident and Magic Plastic Surgery, he is played by Patrick Bergen, leading to this priceless quote:

Lex Luthor: You can change your face, your hair, your voice... but not your DNA. You still sweat the same.

  • In Series 1 and 2 of My Parents are Aliens, Sophie Johnson was played by blonde Barbara Durkin. From Series 3 onwards, she was played by brown-haired Carla Mendonça, having 'got stuck' morphed that way.
  • Holly, the A.I. from Red Dwarf, became a female character at the end of series 2 and stayed female for the next three series.
    • Less noticeable was the recasting of the android Kryten (with Robert Llewellyn replacing David Ross, who originally was to return but was unavailable). This was mainly achieved when the look of the series was entirely redesigned, with a greatly improved budget allowing for better costumes and prosthetics, plus the fact that Kryten was only in one episode previously. Llewellyn played the part very differently, with this being explained in an Opening Scroll as Lister rebuilding him but being unable to restore his personality, this was further explored in Series VIII Episode 2 "Back in the Red: Part 2" when Kryten's behaviour is 'reset' and his actions and mannerism noticeable revert to the 'Ross' Kryten (before being restored to his old new self).
  • British children's comedy Mike And Angelo had Angelo - an alien - go through a regeneration process into another actor that was a direct reference to Doctor Who.
  • Inverted on Babylon 5; at the end of Season 1, Delenn uses an ancient machine to transform herself into a being with both human and Minbari characteristics, radically changing her appearance, but is still played by the same actress. (It gets weirder: the original plan was for Delenn to be a male Minbari, who became female in her transformation...and it was always going to be the same actress, with makeup, effects, and voice manipulation. That part didn't work and was scrapped before filming began.)
    • The male makeup for Delenn is still in the pilot though, mostly in the jawline, the plan fell over at the voice manipulation, which couldn't be made to sound convincing.
        • Technically, the movie Delenn wasn't male, the plan was to have the Minbari as hermaphrodites, and adjusting to being a distinct gender was to have been part of the change.
    • Babylon 5 also messed with the trope in a couple other ways. When the first actor to play Draal was unable to return due to illness, a new one was cast, the difference being remarked upon by Sheridan. Delenn replies that the Great Machine had restored to him his youth and appearance of thirty years prior. When the original actress to play Anna Sheridan was unavailable, they recast her with the real-life wife of the actor playing her onscreen husband, and although the backstory involved would have made it ridiculously easy to hand-wave the change in appearance, they instead played it as The Other Darrin.
      • Fortunately, it was easy not to notice that it was a different actress.
      • Re-shooting the scenes from the earlier appearance (it was an old video Sheridan watched again) helped a lot there. And this video of Anna was the only 30 seconds we had been given of her before her return from Z'ha'dum, so it wasn't like we had a fresh image of her ingrained into our minds.
    • The characters migrate with actor availability as well... Carolyn Sykes becomes Catherine Sakai, becomes Anna Sheridan. JS becomes JS. Rather like the senior telepath/s and the second/s in command. The role continues in other hands - what trope is that?
  • The death of Philip Gilbert shortly into Big Finish's The Tomorrow People line was framed by having TIM require some repair work after damage received in Gilbert's last episode. John had to rebuild TIM's voice synthesizer, and couldn't quite reproduce the original voice. Gilbert's other recurring roles (He also voiced a family of clones on whose voice TIM had been modeled) were not so lucky, and became Fake Shemps.
  • In Lexx, the change from Zev Bellringer to Xev Bellringer was explained via the former dying and melting into a puddle of goo, from which the latter was incarnated via the sacrifice of a few hapless astronauts. The reason given for her being so different in behavior and appearance after the resurrection is that the alien who brought her back was working from the imperfect memories of Zev's friends. It's worth noting that Xev still appears to have all of Zev's original memories, and is still part cluster-lizard due to Zev's botched love-slave transformation. Also, in a later episode Xev is briefly reverted to her original "ugly Zev" body, but later restored to Xev.
  • In Big Bad Beetleborgs, Jo becomes the victim of a botched magical spell that alters her face from that of Shannon Chandler to that of Brittany Konarzewski. The change is permanent but a new spell makes everyone but the other heroes (and the viewer, of course) see her old face.
  • Subverted in a huge way by the Australian lifestyle show parody Life Support. In Season 3, Doctor Rudi changed actors, from Simon Van Der Stap to Jack Finsterer. However, it turned out that this new Dr Rudi, who had allegedly had Magic Plastic Surgery, was actually an impostor, and the old Dr Rudi was out for revenge. it culminated in a fist-fight between the Rudis at the new Dr Rudi and Sigourney's wedding.
  • On 'Allo 'Allo!, Herr Flick was played by Richard Gibson until series 9, when he was replaced by David Janson. To explain the change in actors (who looked nothing alike) Herr Flick had plastic surgery to radically alter his appearance so he would not be captured by Allied forces.
  • Used for numerous minor characters on Stargate SG-1, but this is an acceptable technique as the characters themselves are parasitic aliens (Goa'uld or Tok'ra) living in changable human hosts.
  • Used in Stargate Atlantis for Elizabeth Weir. Previously played by Torri Higginson, Weir returned first as a faceless, fuzzy-voiced Virtual Ghost, who then built herself a replicator body played by Michelle Morgan, who had in the previous season played F.R.A.N., a replicator McKay made. This allowed them to explain that to save time, Weir simply used the last template in the replicator machine, rather than try to remake her own appearance from scratch.
  • The German 90s TV show Balko used this. After the first actor Jochen Horst playing the main character left, the next season started with a near fatal car accident, forcing the till then unseen character to undergo plastic surgery, turning him into new actor Bruno Eyron (among the possible new faces given to choose from was also a famous German shepherd dog, 'Kommisar Rex').
  • Supernatural: Demons can possess different human bodies, so any demon character can be played by more than one actor. It happened with Lilith in Season 3, and then with Ruby/"Kristy" between seasons 3 and 4.
    • It also occurred with villains Azazel and Alastair, and the possibility exists for this to happen with the angels as well. However, it's explicitly avoided with the character of Anna, whose human body was destroyed when she became an angel again, but replaced with an identical one as she'd become attached to it and and arranged for it to be remade.
    • The angels don't just switch bodies, they also don't care about the sex of their physical vessels. Castiel's alternative vessel was a 12 year old girl, Lucifer appeared as a woman in both Sam and Nick's dreams, and Raphael's second vessel was female. Fan theories vary on whether angels simply don't recognize gender in the way humans do or if they have a particular gender preference. But whatever you do, don't bring up the question of what this means for the hetero/homosexuality of ships involving angels.
    • Meg has also gone through several, including Sam's.
  • The Terminator known as Cromartie is reduced to a metal skeleton in the first episode of The Sarah Connor Chronicles, and slowly creates a new flesh covering for himself over the course of the first season, being played by a second actor in the interim stages, and a third actor once the work is complete.
  • Trance from Andromeda is interesting in that it was to change her makeup design instead of her actress. Part way through season two she's replaced with a future version of herself who looks completely different (even having a different skin colour), but she's still the same actress behind the makeup.
    • She still does act fairly differently however (presumably due to her being older and more mature than her previous self).
    • Indeed, the change is so convincing, and done in such a way that is seems like a straight-up example of the trope, you really have to go over the credits to convince yourself it's the same actress!
  • Shapeshifter Candice's favourite form was originally played by Missy Peregrym, but in her brief appearance in season 2 she had decided to change identities, and her new preferred form was Rachel Kimsey.
  • Most Soap Opera actor changes are simply The Other Darrin (or the result of Soap Opera Rapid Aging Syndrome for the younger set), but occasionally they can be Nth Doctors. Example: Jerry Jacks of General Hospital had his Magic Plastic Surgery turn him from Julian Stone to Sebastian Roche...and it was good enough for him to successfully use an alias for a few months.
    • One of the most infamous (and convoluted) versions of this occurred on Days of Our Lives: When Wayne Northrop - the actor portraying Roman Brady - left the show in 1984, his character was Put on a Bus via shooting/body snatching. Two years later, the younger, taller Drake Hogestyn took over the role. Playing this trope straight, they explained his physical differences by plastic surgery needed to recover from the injuries suffered at the hands of Stefano DiMera. Then Northrop returned four years after that... as Roman Brady. He'd been held prisoner by DiMera, while DiMera sent brainwashed mercenary John Black (who, in an extra dash of Soap Operaness, turned out to be Stefano's half-brother) to take over Roman's life and be his spy (That didn't work so well for Stefano). But Northrop only stuck around three more years before leaving again. This time they went straight The Other Darrin and brought in Josh Taylor to play Roman (and has since 1997).
  • Villain Al Hawke returned to Birds of Prey played by a different actor, his new face is explicitly the result of Magic Plastic Surgery to erase the scars of his burns from a previous episode. Unlike other examples, this doesn't explain why his personality, height, etc. all change between appearances, but hey.
  • Joan of Arcadia and The Collector where different actors play God and The Devil, respectively.
  • Two cases in Kamen Rider Den-O: When Hana's actress Yuriko Shiratori left the show for unknown reasons, she was replaced by the much-younger Tamaki Matsumoto, and it was explained that her timeline had been rewritten to make her younger. When Ryotaro's actor Takeru Satoh moved on to other roles after the third movie, he was replaced with Takuya Mizoguchi (who previously played Ryotaro's younger self in the first movie), and the Timey-Wimey Ball was again used to explain it. Interestingly, both Matsumoto and Mizoguchi bear a striking resemblance to their predecessors, a fact which becomes more pronounced as they grow up.
  • Played with in Dollhouse. Many of the 'characters' are, or become, artificial constructs (imprints) that can be moved from body to body. Multiple actors interpret Topher, Dominic, 'Taffy', Dr. Saunders, Clyde Randolf, 'Kiki', Margaret, the serial killer in 'Belle Chose', and Caroline in this way. Generally as much as possible is done to retain the voice and mannerisms of the original, with the exceptions of Clyde and Dr. Saunders, who change and evolve as they go along.
    • In particular, Victor was imprinted with Topher enough times to count as a recurring character.
    • In the post-apocalyptic episodes, Ambrose and Harding are played by different actors than normal, explaining that they now jump bodies ("getting a new suit") regularly and have multiple copies of each other. The same thing was done to Rossum founder Clyde when Rossum was first starting.
  • In Mighty Morphin Power Rangers, Rita Repulsa was originally portrayed using stock footage of Machiko Soga as Witch Bandra from Kyoryu Sentai Zyuranger (with Barbara Goodson dubbing her voice) until the beginning of Season 2 when she was shrunken and imprisoned inside a small space dumpster by her master Lord Zedd. When she returned to full size later during the same season (now played by Carla Perez in all new American-made footage), her servant Finster gave her a magical makeover in order to explain her different appearance.
  • In the Superboy TV series Lex Luthor was Nth Doctored through plastic surgery while Superboy himself was Other Darrined.
  • The final season of My Hero did this with George. Having bet his own body in a poker game, his soul ends up in a replacement.


  • To replace the late Peter Jones in the Tertiary Phase of The Hitchhiker's Guide to the Galaxy, the guide receives an "update" during the first scene of the play. Thanks to some clever editing, the voice of the Guide changes in mid-sentence, and occasionally reverts back for a second, using recycled audio from the original series.
  • The first actor to play The Lone Ranger on the radio died tragically in a car crash. To further a) a seamless transition of the character and b) to keep young viewers from being freaked out by the Ranger's sudden vocal change, the producers decided to have the Ranger be struck mute for a few episodes before introducing the new voice of the Ranger, Brace Beemer.

Web Comics

Western Animation

  • Exception: Transformers often upgrade, and occasionally mutate, into newer, more powerful bodies. The degree to which their new looks resemble their previous style tends to vary, and sometimes they even change their name, as Hot Rod did on becoming Rodimus Prime in The Movie, or like Overhaul did when he became Leobreaker in Cybertron. The voice actors tend to stay the same when this happens, as this is more about selling toys than about recasting.
    • Lampshaded in Beast Wars. Optimus Primal demonstrates all the toys and weapons in his new "Optimal" body, prompting Cheetor to remark that he learns his new bodies fast. Rattrap then remarks (staring directly at the camera) "Why not? He changes them often enough," accompanied by a Rimshot.
    • However, voice actor changes have occurred with upgrading. When G1 Megatron was upgraded into Galvatron in Transformers: The Movie, Galvatron had the voice of Leonard Nimoy. Galvatron in the series proper was still voiced by Frank Welker, though. Also, Scourge and Cyclonus had new voice actors instead of those of Thundercracker and... either of the two characters Cyclonus could be. (Long story.) Beast Machines Jetstorm has a different voice than Silverbolt, because it'd ruin the surprise. And funny you should mention Leobreaker.
    • Transformers Cybertron Red Alert has the same voice actor as the Transformers Armada version, but with a Fake Brit accent.
  • By the time Toonami went off the air, it was being hosted by TOM4. Like the above Transformers example, more often than not there was no change in voice actors, with only the original having a different voice actor.