The Doctor (Doctor Who)
The Doctor is the title character in the long-running BBC science fiction television programme "Doctor Who". Since the show's inception in 1963, the character has been portrayed by thirteen lead actors. In the programme, "the Doctor" is the alias assumed by a centuries-old alien—a Time Lord from the planet Gallifrey—who travels through space and time in the TARDIS, frequently with companions. The transition to each succeeding actor is explained within the show's narrative through the plot device of "regeneration", a biological function of the Time Lord race that allows a change of cellular structure and appearance with recovery following a potentially fatal injury.
History of Doctor Who
A second full series of 13 episodes was commissioned for 2011, with Smith and Gillan both returning as the Doctor and Amy respectively (making it the first time since the show's relaunch in 2005 that both the Doctor and main companion had remained the same from one series to the next). The series was broadcast in two halves, with the first seven episodes broadcast between April and June 2011, and the final six beginning on 27 August 2011. With the new series, Darvill was upgraded to series regular and full-time companion as Rory, and Kingston continued to appear on a recurring basis as River Song.
Due partly to budget restrictions at the BBC, the expected 2012 series, Smith's third, was split into 5 episodes transmitted from September 2012 and a further 8 transmitted from April 2013, with the now traditional Christmas special between these 2 groups of episodes. The advent of the show's 50th anniversary in November 2013 meant that instead of starting to film an 8th series, the BBC started work on a feature-length special, to be transmitted on 23 November 2013, the precise date of the show's 50th anniversary. As well as being made in 3D for presentation at selected cinemas, the episode was also announced to be co-starring David Tennant and Billie Piper, reprising their roles of the Tenth Doctor and Rose, though ultimately Billie Piper played The Moment, a Gallifreyan Weapon that took the form of Rose.