Following two recent additions to Doctor Who lore, past actors such as David Tennant and Matt Smith could return... playing completely different regenerations of The Doctor. As soon as Doctor Who established the concept of regeneration with the fade from William Hartnell to Patrick Troughton in 1966, it became inevitable that a multi-Doctor story would one day materialize. Sure enough, "The Three Doctors" aired to celebrate Doctor Who's 10th anniversary, starting a long-standing TARDIS tradition that continued with "The Five Doctors," "The Two Doctors," "The Day of the Doctor" and more.

Naturally, Doctor Who's multi-Doctor affairs generate intense attention, and viewers are always on the lookout for potential opportunities or anniversaries where a former actor might feasibly return. Unfortunately, sightings of past Doctors are rarer than the Loch Ness Monster. There's a common belief that bringing Time Lords together too often will not only diminish the novelty of such episodes, but also risk undermining the current Doctor by bringing back a super-popular predecessor.

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The introduction of the Timeless Child in Doctor Who season 12, however, carves out a new path for multi-Doctor episodes, where old actors can return to the show as a completely different Doctor. Chris Chibnall's controversial canon retcon at the end of Doctor Who's season 12 finale disproved virtually every known tenet of The Doctor's past. Since the 2021 New Year's special episode skirted around the issue, the jury's still out on whether the Timeless Child is a bold new direction or a miserably pointless rewrite, but whatever the verdict turns out to be, the revelation does promise to shake-up any future returns for the likes of Tennant and Smith.

The Doctor Can Revisit Old Faces When Regenerating

Doctor Who - Tom Baker as The Curator

Celebrating 50 years of Doctor Who, 2013's "The Day of the Doctor" focuses on the trio of Matt Smith's Eleventh Doctor, David Tennant's Tenth Doctor, and John Hurt's brand new War Doctor. Every regeneration up to Peter Capaldi (or his angry eyebrows, at least) features in the finale, though the classic actors are added digitally rather than appearing in person. One legendary Doctor Who actor who does appear in person is Tom Baker, playing a curiously well-informed museum curator and telling the Eleventh Doctor that he might find himself "revisiting a few" faces in the years to come. Baker's cameo suggests The Doctor can retake old forms when he regenerates, but since the moment was intended more as a light-hearted tribute than a lore-shattering revelation, the claim couldn't be taken too seriously.

Nevertheless, Steven Moffat elaborated on the idea during Peter Capaldi's reign as the Twelfth Doctor. Before landing the starring role, Capaldi played Caecilius in "The Fires of Pompeii" during the Tennant era, and while Doctor Who probably could've got away without explaining the visual similarity, the truth would eventually be revealed. After repeatedly musing "why THIS face?" the Twelfth Doctor realized that he made himself look like Caecilius as a reminder of the lessons learned while gallivanting around Pompeii two regenerations ago. Thus, The Doctor's ability to revisit old faces (both his own and others) became canon, retroactively explaining the Sixth Doctor looking like Commander Maxil ( Colin Baker's original character) and the Metacrisis Doctor looking like David Tennant.

Fans speculated that Doctor Who was paving the way for either David Tennent or Matt Smith to return as the Thirteenth or Fourteenth Doctor, effectively picking up where they left off. Sadly, that was always an outlandish suggestion.

The Timeless Child Means There Are Numerous Unseen Past Doctors

Doctor Who Timeless Child

According to the Timeless Child explanation from Doctor Who season 12, The Doctor was not born on Gallifrey. She fell through a portal from an unknown place and was adopted by a Gallifreyan. At this time, the planet's population could not regenerate or travel through time; those powers were instead harnessed from The Doctor's natural biology, with the mysterious traveler seemingly possessing endless lives. After growing into adulthood, The Doctor was chosen to join a shady Time Lord agency called The Division, but after a messy falling out and several memory wipes, the future hero of the universe ran away from Gallifrey in the guise of William Hartnell and never looked back.

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Since Doctor Who has now confirmed the First Doctor was actually more like the 31st Doctor, there are any number of unseen, older regenerations out there meddling with time and space on behalf of The Division. Jo Martin's "Fugitive Doctor" is almost certainly one of them. But if every one of those historic Doctors were to line up, would they all have new, unrecognizable faces? According to Moffat, that's unlikely. If The Doctor is capable of influencing the appearance of a regeneration (like Capaldi) or liable to revisit an old favorite (like The Curator), it's perfectly possible that at least of one of those pre-Hartnell iterations might've looked like the Tenth Doctor, or the Eleventh, or the Sixth, etc.

Combining Moffat's face recycling with Chibnall's Timeless Child creates an exciting range of fresh story possibilities for future multi-Doctor episodes of Doctor Who.

Why Past Actors Playing New (Old) Doctors Is Better For The Show

The Five Doctors in Doctor Who

As wonderful as seeing old Doctors might be in Doctor Who's anniversary specials, there's obviously a strong whiff of nostalgia in each. The script is also obliged to explain any inconsistencies. There's a built-in reason for why past Doctors don't remember meeting their future selves (something about the laws of time travel), but Doctor Who has struggled to account for why returning actors sometimes look older. Recasting a past actors as a pre-Hartnell Doctor would alleviate these problems, since they'd be playing a Doctor the audience has never met.

As an example, Sylvester McCoy is quite a bit older than he was during the Seventh Doctor's regeneration in 1996, and it's unlikely he'd get away with playing his Doctor again on TV. But if the Seventh Doctor's face was actually a "revisit" from an old, forgotten regeneration, McCoy could appear in a future multi-Doctor episode and his aged appearance wouldn't be a plot hole. The same applies for every other surviving Doctor Who lead actor.

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Legacy actors might be more tempted to return to the Doctor Who fold if given the opportunity to create an entirely new character. Whenever a Doctor makes a comeback, they're obliged to roll out the same old mannerisms and catchphrases fans know and love. Playing a new (although technically older) regeneration promises more creative freedom and innovation for the returnee, while also offers a tantalizing "what if" for the audience. What if the Tenth Doctor was harsh and severe like the First? What if the Eleventh Doctor took a darker turn, becoming as jaded and angry as the War Doctor? By casting familiar faces as The Doctor's past regenerations, Doctor Who can explore these possibilities and bring back beloved former stars while still being progressive and forward-thinking.

One possibility is making the Division Doctors villains, since the Time Lord agency is clearly not to be trusted. Doctor Who's future could see Jodie Whittaker going up against a villainous Division regeneration played by David Tennant, Matt Smith, or even the great Tom Baker.

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