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.
Jack Harkness
Captain Jack Harkness is a fictional character played by John Barrowman in "Doctor Who" and its spin-off series, "Torchwood". The character first appears in the 2005 "Doctor Who" episode "The Empty Child" and subsequently features in the remaining episodes of the 2005 series as a companion to the series' protagonist, the Doctor. Subsequent to this, Jack became the central character in the adult-themed "Torchwood", which aired from 2006 to 2011. Barrowman also reprised the role for guest appearances in "Doctor Who" in its 2007 series and 2008 series, as well as the two-part special "The End of Time".