Tom Baker as The Doctor

Elisabeth Sladen as Sarah Jane Smith

Ian Marter as Harry Sullivan

Nicholas Courtney as Brigadier Lethbridge-Stewart

John Levene as RSM Benton

Patricia Maynard as Miss Winters

Michael Kilgarriff as The Robot

Edward Burnham as Professor Kettlewell

Alec Linstead as Jellicoe

Timothy Craven as Short

Clive Barrie as Phillips

Walter Goodman as Joseph Chambers

Jon Pertwee as The Doctor