The Doctor will come face to face with his past in the Doctor Who Christmas special. A new teaser trailer released at San Diego Comic-Con, also reveals the episode will be titled 'Twice Upon a Time.' Doctor Who season ten ended with the current Doctor, Peter Capaldi, desperately trying to stave off his regeneration. Stumbling from the TARDIS, he went outside and plunged his hands into the snow, stating he wasn't ready to go. At that point, the first Doctor - played by David Bradley in an uncanny likeness to the late William Hartnell - appeared and reminded him that it was futile to try and stop it.
Fans have known for some time that Bradley will play a part in the upcoming Christmas special, which is also when Capaldi will regenerate into the thirteenth Doctor, to be played by Jodie Whittaker. While she is not seen in this first teaser for the Christmas special, Bill Potts is. That will certainly be pleasing to fans, who felt that Pearl Mackie didn't get a good enough send off at the end of season 10, and that there wasn't a fond farewell between Bill and the Doctor.
Also featured in the Christmas cast is Mark Gatiss as The Captain, who is seemingly one of the only people not frozen in time. The short teaser is packed full of drama, with plenty of explosions. This will be the last episode for Capaldi and also for showrunner Steven Moffat, and, given that it's a Christmas special, we can expect an enjoyable enough story before the regeneration actually happens. Certainly the prospect of two Doctors traveling through time and space together is an exciting one. It'll also be interesting to see exactly how they manage to stave off Twelve's regeneration long enough for an actual storyline to take place since it seemed pretty well underway at the end of season ten.
Speaking at the Doctor Who San Diego Comic-Con panel, Moffat said the teaser also hints at multiple Doctors "refusing to regenerate." During the panel, the opportunity arose for Moffat to praise Capaldi's performance as the Doctor, and a highlight reel was also released, as can be seen below.
— BBC America (@BBCAMERICA) July 23, 2017
Elsewhere, Mackie confirmed that Bill Potts will not be returning; a great sadness and loss to Doctor Who, but also tremendously exciting since it now paves the way for Whittaker's Doctor to have her own companion; male, female, or otherwise, but completely brand new. Still, for now, Capaldi is the Doctor, and Bill his companion. The highlight of the impressive Christmas special teaser was undoubtedly their joyful hug, and seeing them reunited is going to be thoroughly uplifting. The only trouble with that is, then they have to say goodbye.
Doctor Who will return to BBC 1 and BBC America this Christmas. Season 11 is expected to arrive mid-2018.