The Twelfth Doctor is an alien.
The Doctor is the title character and protagonist in the long-running BBC science fiction television programme Doctor Who . 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 his TARDIS , frequently with companions . The character has been generally well received by the public , with his enduring popularity leading The Daily Telegraph to dub him `` Britain 's favourite alien '' . The Twelfth Doctor is an incarnation of the Doctor , the protagonist of the BBC science fiction television programme Doctor Who .