John Hurt
From Tardis Wiki, the free Doctor Who reference
John Hurt played an unknown incarnation of the Doctor in TV: The Name of the Doctor.
Within the Doctor Who universe
John Hurt exists as an individual within the Doctor Who universe. In TV: Greeks Bearing Gifts, Toshiko Sato compared the body of a dead soldier with his heart ripped out to "that bit in Alien where that thing bursts out of John Hurt."
Also, in "Coupling", which was written by Moffat, Hurt is mentioned in context of giving birth, and the scene from "Alien".
Furthermore, in TV:The Name of the Doctor Hurt was revealed to be playing an as yet unrevealed incarnation of The Doctor.
