The Twelfth Doctor is an incarnation of the Doctor, the protagonist of the BBC science fiction television programme Doctor Who. He is portrayed by Scottish actor Peter Capaldi. Within the series' narrative, the Doctor is a time travelling, humanoid alien from a race known as the Time Lords. At the end of life, the Doctor can regenerate his body, and in doing so gain a new physical appearance, and with it a distinct new personality; this plot mechanism has allowed the Doctor to be portrayed by a series of actors over the decades since the programme's inception in 1963. Capaldi's portrayal of the Doctor is a spiky, brusque, contemplative, and pragmatic character who conceals his emotions in the course of making tough and sometimes ruthless decisions.