an Entity references as follows:
The Fifth Doctor is an incarnation of the Doctor, the protagonist of the BBC science fiction television series Doctor Who. He is portrayed by Peter Davison. Within the series' narrative, the Doctor is a centuries-old alien Time Lord from the planet Gallifrey who travels in time and space in the TARDIS, frequently with companions. At the end of life, the Doctor regenerates; as a result, the physical appearance and personality of the Doctor changes.