Third Doctor See List of non-televised Third Doctor stories. Third Doctor The Third Doctor is an incarnation of the Doctor, the protagonist of the BBC science fiction television series "Doctor Who". He was portrayed by actor Jon Pertwee. 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. At the end of life, the Doctor can regenerate his body; as a result, his physical appearance and personality change. Pertwee portrays the third such incarnation, a dapper man of action of stark contrast to his
Enlightenment (Doctor Who) serial "Mawdryn Undead", and concluding with "Enlightenment"), the enemy was the Black Guardian, who was last encountered by the fourth incarnation of the Doctor at the conclusion of The Key to Time saga in the 1979 serial "The Armageddon Factor". The story also saw the return of the White Guardian, who had also not been seen since 1979. After penning a number of radio and TV scripts, including episodes of "Crossroads" and "Waggoner's Walk", Barbara Clegg submitted a story idea to "Doctor Who" script editor Eric Saward, an acquaintance from the BBC drama department. Interested in writing for the series,