Second Doctor
The Second Doctor is an incarnation of the Doctor, the protagonist of the BBC science fiction television series Doctor Who. He was portrayed by character actor Patrick Troughton.
Within the series' narrative, the Doctor is a centuries-old Time Lord alien from the planet Gallifrey who travels in time and space in his TARDIS, frequently with companions. When the Doctor is critically injured, he can regenerate his body; in doing so, his physical appearance and personality change.