Even though they had just finished filming the Christmas special “Twice Upon a Time,” Doctor Who brought a small glimpse of it to Comic-Con — along with the news that Pearl Mackie would return as Bill, and Mark Gatiss would be appearing in it.
Steven Moffat, in what will be his last Doctor Who Comic-Con as a the showrunner, said that the episode is about the Doctor refusing to regenerate and going on an adventure with Mark Gatiss.
Something has gone very wrong with time.
The Doctors and Bill return this Christmas in ‘Twice Upon A Time’. #DoctorWho pic.twitter.com/iTpAesJbx7— BBC America (@BBCAMERICA) July 23, 2017
All of this was a goodbye to Moffat and Peter Capaldi, also in his last Hall H appearance as the current doctor, and even Mackie, who confirmed that this will be Bill’s last outing.