The Doctor (Doctor Who)
Jodie Whittaker took over the role as the Thirteenth Doctor in the 2017 Christmas special. In addition to the above-listed actors, others have played versions of the Doctor for the duration of particular storylines.
Notably, John Hurt guest starred as the War Doctor in the closing moments of the 2013 episode "The Name of the Doctor", the webcast "The Night of the Doctor" and the 50th Anniversary episode "The Day of the Doctor". The War Doctor is an incarnation existing between those of McGann and Eccleston. Hurt was never the programme's lead actor; his Doctor was retroactively inserted into continuity for the programme's 50th anniversary, and was written so as not to disturb the ordinal naming of the established Ninth, Tenth and Eleventh Doctors. In the 1986 serial "The Trial of a Time Lord", Michael Jayston played the Valeyard, an amalgamation of the Doctor's darker sides from between his twelfth and final incarnations.
Twelfth Doctor
Capaldi has previously appeared playing other roles in the "Doctor Who" franchise. He portrayed Lobus Caecilius in the 2008 episode "The Fires of Pompeii" and John Frobisher in "", the 2009 serial of the "Doctor Who" spin-off "Torchwood". Moffat has stated that he plans on explaining over time why there are three characters in the "Doctor Who" universe with the same appearance; his predecessor Russell T Davies had once explained to him a theory for the first two, and upon Capaldi's casting assured Moffat that the explanation would still work. This situation was alluded to in "Deep Breath", when a confused Doctor is reminded of Caecilius when he examines his face in a mirror. In "The Girl Who Died", it is explained that the Doctor chose Caecilius' face to remind himself that he is the Doctor, and that he can always save people. While not explained in the episode, Moffat later said that he also shares a face with John Frobisher as Frobisher is Caecilius's descendant, and represents the end of Caecilius's bloodline, referencing the Doctor's "eternal battle with doom and destiny." Capaldi's casting marks the second time an actor has previously appeared in the series and then been cast as an incarnation of the Doctor, the first being Colin Baker.