In May 2022, BBC announced the next actor to take on the mantle of Doctor Who: Ncuti Gatwa. Gatwa is a young breakout star best known for his appearance in Netflix's Sex Education. Notably, around the same time as BBC's major casting announcement, the network also announced that David Tennant would be returning to the show at a later date. After the casting announcement, fans began to prepare for the inevitable regeneration of Jodie Whittaker's Thirteenth Doctor into Ncuti Gatwa's Fourteenth Doctor during the centenary special, "The Power of The Doctor." However, Jodie Whittaker regenerated into an entirely unexpected character: the Tenth Doctor.
For context, Tennant portrayed the Tenth Doctor from 2005-2010, ultimately culminating in a three-season, forty-seven-episode run. His performance was unprecedented and critically well-received. Where Christopher Eccleston brought the series back to life in 2005, Tennant won over millions of fans with his performance. His portrayal of the Tenth Doctor earned him the National Television Awards award for Most Popular Actor in 2006 and 2007 and the Outstanding Drama Performance award in 2008 and 2010. Fan publications unequivocally voted him as the best Doctor or the best actor in the role of the Doctor, including Doctor Who Magazine, IGN, Daily Mirror, Radio Times, Plusnet, DoctorWhoTV, DigitalSpy, and The Telegraph.
When Tennant left the show in 2010, the showrunners considered ending the series out of fear that it would fail without Tennant. Suffice it to say, David Tennant's run on Doctor Who was a tremendous deal. While some fans are teeming with excitement for Tennant's return, others are confused. How is this possible? Did Whittaker de-generate into the Tenth Doctor? Does this mean that any past Doctor could potentially return? Has this always been possible? Is this really the Doctor's doing, or could this be the Master at work? While there are no official answers yet, here are some likely explanations for how the Tenth (now Fourteenth) Doctor returned.
Update October 1, 2023: This article has been updated following the recent 60th Anniversary trailer for David Tennant's Doctor Who specials.
David Tennant's Isn’t the First Doctor to Return
"The Power of The Doctor" established David Tennant as the next regeneration, adorned in his signature Converse, a formal suit, and a large blue overcoat — symbolic of the Tenth Doctor's wardrobe. While a regeneration into a previous doctor is unheard of, this isn't the first time stars have returned to the show.
Doctor Who: New Era Regenerations, Ranked
The new Doctor Who series has been airing for 18 years and has featured multiple regenerations. These are the best ones, ranked.For instance, the thirtieth-anniversary special in 1993 featured every living former Doctor (Jon Pertwee, Tom Baker, Peter Davison, Colin Baker, and Sylvester McCoy) and dozens of former companions. Later, Matt Smith returned as the Eleventh Doctor in "Deep Breath" during a phone call to the Twelfth Doctor (Peter Capaldi). Most notably, Tom Baker — arguably the overall second-favorite Doctor — reprised his role as the Fourth Doctor in 2013. This epic crossover included Baker, Tennant, and Smith in the fiftieth anniversary special "The Day of The Doctor." What all of these features share is that the actors remained in the roles they originally had.
Canonically, the Twelfth Doctor's phone call to the Thirteenth is the previous Doctor calling the next Doctor at a point in time when they both existed. Even though the canon is not entirely clear on the space-time continuum legitimacy of these crossovers, the appearances remain separate and distinct in character portrayal. Therefore, David Tennant's return is unlike previous Doctor Who homecomings.
Regeneration Gone Sideways
Canonically, when each Time Lord regenerates, they maintain some semblance of awareness. They understand when it is imminently happening, often allowing them to warn companions or give a last heart-wrenching performance. To many fans, this process seems random; the Doctor does not know anything about their next form, nor can they predict when their future regeneration will be. Arguably, those fans are right: it is random.
The regenerations are scattered throughout the series with little to no foreshadowing. Each is unique and bittersweet, but they all follow the same canter. Some mundane (or traumatic) event occurs, the Doctor and their clothing regenerate with a flash of temporal energy, and they curiously examine their new form.
That is in no way what happened in "The Power of The Doctor." The Doctor appeared disoriented, shocked, and bewildered. One of the biggest hints that something damaged the regenerative process is that the Doctor's clothing regenerated. Beyond the first-ever regeneration, the Doctor has always transformed while wearing the previous iteration's outfit. For example, David Tennant appeared in Christopher Eccleston's signature leather jacket, and Matt Smith appeared in David Tennant's quirky formal attire. This, coupled with a clip from the trailer where Ncuti Gatwa's Doctor yells, "Will someone tell me what the hell is going on here?!" shows that something has gone drastically wrong.
Is Someone Behind This?
One of the earlier fan theories pointed at the Master. In the season finale, The Thirteenth Doctor battled The Master, a rogue Time Lord intent on stealing the Doctor's infinite regenerations through a process called "forced regeneration." This ultimately failed, and the Doctor regained control of her body. Because the regenerative process started so soon after this, it's possible that the Master disrupted or even damaged the Doctor's ability to safely regenerate during their battle. While this is possible, the snafu with the Master most likely triggered the regeneration rather than causing any damage.
If it's not the Master, it's likely the Toymaker, Tennant's antagonist for the sixtieth-anniversary special. The celestial Toymaker, portrayed by Neil Patrick Harris, is imbued with the power to rewrite reality itself. He is known for entangling innocent beings into high-stakes games of his own creation, often rigged in his favor. When Tennant appears on-screen, lost, confused, and in a state of disbelief, it seems like someone is toying with his perception of reality. Later, the trailer shows Ncuti Gatwa's Doctor standing on what looks to be the same cliff upon which Tennant appeared. Moreover, Gatwa appears to be wearing the same shirt and tie as Tennant. Therefore, Gatwa's regeneration did not alter his clothing.
What if the appearance of Tennant is an illusion by the Toymaker, and Gatwa has been in existence the whole time? Could this be one of the Toymaker's signature games? Could this all be happening on the same psychic, astral plane as seen in "The Power of The Doctor?"
One twitter theory again suggests the Fourteenth Doctor is a result of The Toymaker's interference, and the only way the Doctor can save Donna this time is by erasing his own existence "by resetting to the moment of 13's regeneration." However, since all Doctors remember their previous incarnations, the Fifteenth Doctor will consider himself Fifteen. Some fans hope this will also offer a way to retcon the unpopular Timeless Child storyline from the Thirteenth's time as Doctor.
Tie Up Lose Threads
The most recent trailer for the sixtieth anniversary's three special episodes just dropped and offered a few more clues to fuel fan theories. In the trailer, Donna Noble — whose memory was wiped by the Doctor to save her life — is shown questioning why she feels she's lost something. Later, it's obvious she's regained her memory as she makes a knowledgeable comment about the TARDIS. The Doctor also tells her, "I don't know if I can save your life this time." The three special episode names have also been released: "The Star Beast," "Wild Blue Yonder," and "The Giggle."
One major thing to note is Tennant's Doctor is not labeled as the Tenth Doctor as he previously was. This is the Fourteenth Incarnation, meaning he is a new Doctor. He also is returning in a storyline involving Donna Noble, a plot thread that was left dangling from his original run on the series. The Doctor might have taken his previous face form as his subconscious telling him he needs to reunite with Donna.
This explanation was used to explain why the Twelfth Doctor looked like Peter Capaldi, who previously played a separate character in the David Tennant episode "The Fires of Pompeii." The Doctor says this was his subconscious, choosing the face as a reminder that his job is to save lives, as the Doctor saved Capaldi's character and his family from dying in Pompeii. Now, though, it might be that the Doctor has some unfinished business with Donna Nobel.
The sixtieth-anniversary special is set to premiere in November 2023, leaving audiences less than a few months to continue speculating. The upcoming special also marks the return of veteran Doctor Who writer and showrunner Russell T. Davies. He has teased the feature's plot, promising to build on the past of Doctor Who as he begins the new iteration. With Davies's return, the revival of the "classic-who" Toymaker, and the return of a fan-favorite doctor, there is plenty to look forward to in November!