Originally invented as a way of writing William Hartnell out due to illness, regeneration has become one of the hallmarks of Doctor Who’s long run on television.
Ever since the Doctor morphed into Patrick Troughton back in 1966, this unique knack for self-renewal has come to mean that each series lead is replaced by a new man or woman when their tenure is finished.
This Sunday’s The Power Of The Doctor marks the end of Jodie Whittaker’s run as the Thirteenth Doctor on TV.
Read more: Why is Jodie Whittaker leaving Doctor Who?
While the exact details of how she regenerates are being kept under wraps until broadcast, there’s a long history of the series sending off its leads in a blaze of glory.
1966: The First Doctor, William Hartnell: “It’s far from being all over…”
Regeneration is only lightly foreshadowed throughout The Tenth Planet, a story that’s a landmark in more than one way because it also features the first appearance of the Cybermen.
With Hartnell’s Doctor notably tired and worn-out throughout the serial, (his penultimate episode doesn’t feature him at all, to give the actor a week off to rest) it falls to companions Ben (Michael Craze) and Polly (Anneke Wills) to keep the cool, logical cyborgs and the erratic, emotional human soldiers from destroying both worlds.
It’s only a shame that the final is one of umpteen classic episodes missing from the BBC archive, but the 2013 animated reconstruction gives us an idea of how shocking it must have been for younger viewers when the Time Lord collapsed in the TARDIS and became someone new…
1969: The Second Doctor, Patrick Troughton: “You can’t just change what I look like without consulting me!”
A few years later, Patrick Troughton’s Second Doctor met his end after three seasons in a whopping 10-part epic, 1969’s The War Games. In the serial, a warmongering race is simulating Earth conflicts in a controlled environment to study them for their bid at galactic domination.
They pose a threat so great that the Doctor has to call the Time Lords for help, effectively turning himself over to their judgement for his original desertion. It’s a sacrifice that costs him his friends Jamie McCrimmon (Frazier Hines) and Zoe Heriot (Wendy Padbury), his TARDIS, and his current incarnation.
The War Games is the first time the series gets specific about the Doctor’s people and planet, but it also forces a regeneration of the show in time for its switch to colour – exiled by his people, the Doctor spends the next couple of seasons adventuring on Earth in the 1970s…
1974: The Third Doctor, Jon Pertwee: “I had to face my fear. That was more important than just going on living.”
The original intention for Jon Pertwee’s eventual departure from Doctor Who was a final confrontation with the Master, originally played by Roger Delgado. Tragically, Delgado died before this plan came to fruition and Pertwee decided to call it a day after five seasons.
Instead, his final story — Planet of the Spiders — weaves together some other loose threads, focusing on a scheme by the mind-controlling spiders of Metebelis III. Having provoked the “Eight Legs” in a previous adventure, the Doctor feels determined to return to this hostile environment to save humanity one last time.
With regeneration now established, this is an ending where the Doctor gets to go out being himself, making things right and being true to that “never cruel, never cowardly” characteristic that would later become a mantra for writers who grew up watching these stories.
1981: The Fourth Doctor, Tom Baker: “It’s the end. But the moment has been prepared for…”
Unquestionably the most iconic incarnation to date, Tom Baker’s Fourth Doctor appeared throughout the rest of the decade and finally hung up his massive scarf in 1981, after seven seasons in the TARDIS. His final run has a story arc about entropy and the unravelling of the universe, culminating in Logopolis.
With companions Adric, (Matthew Waterhouse) Nyssa, (Sarah Sutton) and Tegan (Janet Fielding) in tow, the Doctor alternately battles and allies with a renewed Master (Anthony Ainley) to prevent total universal collapse, culminating in a fateful confrontation atop the radio telescope at Jodrell Bank.
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This regeneration would have been huge to kids who grew up only knowing Baker as the Doctor. Uniquely, the story also includes a mysterious Watcher figure, whose purpose only becomes apparent in the final moments, as the Fourth Doctor’s life flashes before his eyes and the new man arrives…
1984: The Fifth Doctor, Peter Davison: “I might regenerate, I don’t know. Feels different this time.”
Peter Davison’s Fifth Doctor is often remembered as more of a lightweight, but truthfully, his era is quite spectacularly grim. He may usually greet the universe with a smile, but after a particularly harrowing run of adventures, 1984’s The Caves Of Androzani pushes him to the end of his tether.
Hall-of-fame classic Who writer Robert Holmes crafts an action-packed political thriller where the arrival of the TARDIS only makes things worse for everyone, as a dispute between a Spectrox mining corporation and disfigured insurgent Sharaz Jek (Christopher Gable) turns violent, with the Doctor and new companion Peri Brown (Nicola Bryant) stuck in the middle.
It’s a high point of this era, but not a cheerful one. Almost every character dies – including the Fifth Doctor, who succumbs to Spectrox poisoning after giving Peri the only dose of the antidote.
1987: The Sixth Doctor, Colin Baker: “Carrot juice? Carrot juice, carrot juice, carrot juice…”
There’s much to be said elsewhere about Colin Baker’s tumultuous two seasons on Doctor Who, but with the series’ future in doubt, the production team opted to cancel his contract and kill off the Sixth Doctor at the start of the 1987 run. The quote above was his unassuming last line in the previous season and, as it turns out, altogether.
Time And The Rani is unique as a regeneration story in that the change happens at the beginning and we spend most of the adventure with Sylvester McCoy’s Seventh Doctor instead. But the truly weird, never-to-be-repeated aspect of this is that Baker didn’t get to come back at all, so the regeneration scene starts with a prone McCoy wearing Baker’s costume and a curly blond wig.
It's embarrassing all around, especially as the series’ poor reception at the time wasn’t Baker’s fault. With better writers and stories, the Sixth Doctor has duly been reassessed through his run in Big Finish audio plays and even got a proper swansong in 2015’s The Last Adventure.
1996: The Seventh Doctor, Sylvester McCoy: “No, I’m not human. I’m not human.”
By contrast, McCoy was given the utmost consideration in the 1996 US TV movie that sought to revive Doctor Who. Paul McGann’s Eighth Doctor only arrives half an hour into the movie, after an extended first act that sees the Seventh Doctor crash the TARDIS in San Francisco on New Year’s Eve 1999.
Producers originally wanted the more recognisable Tom Baker to return as “the Old Doctor”, as McCoy is credited, but continuity won out. And so, he gets a send-off that’s dripping with dramatic irony, as this most strategically minded of Doctors blunders into a shootout and is later finished off by the well-meaning surgeons who try to save his life.
2013: The Eighth Doctor, Paul McGann and The War Doctor, John Hurt: “Physician, heal thyself”
Although the TV Movie didn’t lead to a series, McGann’s place in the series’ history was secure. Like other Doctors, he continued his adventures in audio dramas produced by Big Finish, but it wouldn’t be until 2013 that he got to come back and join up his incarnation with the 2005 revival.
By way of introducing the newly created War Doctor, Steven Moffat wrote The Night Of The Doctor, which featured McGann’s Doctor trying to save a doomed pilot at the height of the Time War. The minisode sees the dying Doctor realise that this universe needs a warrior, consenting to a designer regeneration that transforms him into a young John Hurt.
The 50th-anniversary special The Day Of The Doctor tells the whole story of this mayfly incarnation and his George Bailey-esque glimpse of a future in which he believes he destroyed Gallifrey.
Things pan out a little differently than remembered and the War Doctor’s final scene closes the gap between the original run and the revival.
2005: The Ninth Doctor, Christopher Eccleston: “Before I go I just wanna tell you, you were fantastic. Absolutely fantastic. And do you know what? So was I.”
Jumping backwards again, the 2005 revival was both rapturously received by critics and audiences and slightly overshadowed by the premature announcement that Christopher Eccleston leave the show at the end of the first season.
Bad Wolf and The Parting Of The Ways closes the Ninth Doctor’s arc nicely, pitting him against the Daleks again and revealing him not as a crass, mindless avenger of the Time War, but someone who’s found himself through his friendship with Rose Tyler (Billie Piper). He dies saving her, instead of destroying everything.
Rather than falling at the first hurdle, the show made the tradition of regeneration part of the language of Doctor Who for a new audience from the start. Eccleston has recently reprised the role for Big Finish, but his final TV adventure pulls off the feat of giving a graceful and satisfying ending to a Doctor we hoped we’d be seeing a lot more.
2010: The Tenth Doctor, David Tennant (twice): “I don’t want to go.”
David Tennant's Doctor was so popular, they killed him twice. The Stolen Earth ends on Doctor Who’s most audacious cliffhanger ever, where the Tenth Doctor’s reunion with Rose was cut short by a Dalek blast and the credits screech in during his regeneration. Through a bit of Doctorish flim-flam involving a spare hand, he remains himself in the following episode, Journey’s End, but later episodes canonise this as one of the Doctor’s original regenerations.
Tennant announced he was leaving for real ahead of a series of specials in 2009, culminating with the Christmas and New Year double-bill The End Of Time Part One and Part Two. Wilfred Mott (the late, great Bernard Cribbins) is the companion, with fateful consequences for the Tenth Doctor as he battles Time Lord characters old and new.
Also tying up various threads from outgoing showrunner Russell T. Davies’ era, the finale is suitably massive. However, both Davies and Tennant are involved in next year’s 60th-anniversary specials, so maybe there’s more to say there…
2013: The Eleventh Doctor, Matt Smith: “I will always remember when the Doctor was me.”
First broadcast a month after The Day Of The Doctor, Matt Smith’s swansong is still on the comedown even though it’s still a big epic Christmas Day special. Writer Steven Moffat planned the Eleventh Doctor’s story arc around the timey-wimey fallout of his eventual death, so there’s a lot to pack into an hour-long special.
Staged between an awkward Christmas dinner with Clara Oswald (Jenna Coleman) and a planet that’s broadcasting a message across all of time and space, The Time Of The Doctor pits the Doctor against Daleks, Cybermen, Weeping Angels, and a host of other enemies who’ve come to ensure he’ll die before he ever lets the Time Lords back into the universe.
Smith’s tenure begins with him leaving Amy Pond (Karen Gillan) behind as a child, so it’s a fitting end that he has to stay in one place for the good of everyone.
Among other things, Moffat uses this story to bust the old “13 incarnations” lore that hung around the series, gifting the Doctor with a new regeneration cycle at its climax.
2017: Peter Capaldi, The Twelfth Doctor: “Doctor, I let you go”
When Peter Capaldi’s Twelfth Doctor departs three seasons later, he’s the third Doctor in a row to depart at Christmas and also filibuster their regeneration, keeping going even as that familiar gold glow keeps creeping up on them.
But 2017’s Twice Upon A Time is more epilogue than climax, reflecting upon the Twelfth Doctor’s type and even further back. Indeed, it comes full circle back to the very first regeneration story, with David Bradley starring as the First Doctor circa the end of The Tenth Planet.
All regeneration stories are technically multi-Doctor stories, but this Christmas special (the last to date) encompasses the hopes and fears of all the years and walks the series up to its biggest change yet, and the arrival of Jodie Whittaker as the first female Doctor.
2021: Jodie Whittaker, The Thirteenth Doctor
Timed to coincide with the BBC's Centenary celebrations, Jodie Whittaker's regeneration is expected to happen during the feature-length special The Power of the Doctor, airing on 23 October, 2022. The first female Doctor will exit the TARDIS at the same time as showrunner Chirs Chibnall, in the episode which sees the Time Lord facing the Master, Daleks, and Cybermen together.
How she goes out is unclear at the moment, as is exactly who she'll regenerate into. In May, 2022, Sex Education star Ncuti Gatwa was carefully announced by the BBC as the 'new Doctor', but not the 'next Doctor'. And with David Tennant returning to the role alongside Catherine Tate's Donna Noble for an upcoming Doctor Who special, expect surprises this time around.
Talking about the final moments of The Power of the Doctor, Chibnall said: "I'm lucky enough to have seen the full ending of The Power of the Doctor and even the tiny bit of the end just made me thrilled about and excited and desperate to see more about what comes next.
"It’s a delightful prospect!"
Doctor Who - The Power of the Doctor will air at 7:30pm on Sunday, 23 October on BBC One. Watch a trailer below.