Doctor Who is a British science-fiction television programme produced by the BBC since 1963. The programme depicts the adventures of the Doctor, a Time Lord—a space and time-travelling humanoid alien. He explores the universe in his TARDIS, a sentient time-travelling space ship. Its exterior appears as a blue British police box, which was a common sight in Britain in 1963 when the series first aired. Accompanied by companions, the Doctor combats a variety of foes, while working to save civilisations and help people in need.
The show is a significant part of British popular culture, and elsewhere it has become a cult television favourite. The show has influenced generations of British television professionals, many of whom grew up watching the series. The programme originally ran from 1963 to 1989. There was an unsuccessful attempt to revive regular production in 1996 with a backdoor pilot, in the form of a television film. The programme was relaunched in 2005 by Russell T Davies, who was showrunner and head writer for the first five years of its revival, produced in-house by BBC Wales in Cardiff. The first series of the 21st century featured Christopher Eccleston in the title role and was produced by the BBC. Doctor Who also spawned spin-offs in multiple media, including Torchwood (2006–2011) and The Sarah Jane Adventures (2007–2011), both created by Russell T Davies; K-9 (2009–2010); and a single pilot episode of K-9 and Company (1981). There also have been many spoofs and cultural references to the character in other media.
Twelve actors have headlined the series as the Doctor. The transition from one actor to another is written into the plot of the show, as well as the differing approach to the role that each brings, under the concept of regeneration into a new incarnation. The show’s premise is that this is a life process of Time Lords through which the character of the Doctor takes on a new body and, to some extent, new personality, which occurs after sustaining an injury which would be fatal to most other species. Each actor’s portrayal differs, but they are all intended to be aspects of the same character and form part of the same storyline. The time-travelling nature of the plot means that, on occasion, different Doctors have met each other. Peter Capaldi took on the role after Matt Smith’s exit in the 2013 Christmas special “The Time of the Doctor”.