In which 1971 serial did the Master first appear?

The Master first appeared in the 1971 Doctor Who serial Terror of the Autons. The story introduced him as a renegade Time Lord and established his long-running rivalry with Jon Pertwee’s Third Doctor.

Broadcast in four weekly episodes from 2 to 23 January 1971, Terror of the Autons begins the programme’s eighth season. The Master arrives on Earth, steals a Nestene energy unit and attempts to use a radio telescope to summon an invasion. His plan brings him into conflict with the Doctor and UNIT, while the story also features the Autons and introduces Jo Grant and Captain Mike Yates.

The Master was conceived as a Moriarty-like counterpart to the Doctor: equally intelligent and resourceful, but willing to use manipulation and violence. Roger Delgado originated the role and played the Master throughout much of the Third Doctor’s era. The Daemons, The Sea Devils and The Claws of Axos all feature later Master stories, but none is his debut.