Press release from BBC America, July 23, 2017:
Today, BBC AMERICA released the first-look teaser of the highly anticipated Doctor Who Christmas Special, as well as a trailer of Peter Capaldi as the 12th Doctor, during its Hall H panel at San Diego Comic-Con.
In addition, it was revealed that Peter Capaldi’s final episode of Doctor Who this Christmas will feature Pearl Mackie as Bill Potts and is titled ‘Twice Upon a Time.’ Viewers will have to wait until Christmas to discover exactly how Bill, who will appear throughout the episode, makes her return.
It was also revealed that the special will co-star Mark Gatiss in a guest role – as a World War One soldier, known so far only as ‘The Captain.’
As previously revealed in the closing moments of the season finale, the special will feature Peter Capaldi’s current Doctor teaming up with the First Doctor, played by David Bradley.
BBC AMERICA’s Doctor Who panel in Hall H on Sunday, July 23, featured Peter Capaldi, Pearl Mackie, Matt Lucas, Michelle Gomez, Mark Gatiss and lead writer and executive producer Steven Moffat.