The Doctor is an alien.
The Tenth Doctor is an incarnation of the Doctor , the protagonist of the BBC science fiction television programme Doctor Who , who is played by David Tennant in three series as well as nine specials . The Doctor is the title character and protagonist in the long-running BBC science fiction television programme Doctor Who . 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 .