The Doctor
Tom Baker
Leela
Louise Jameson
K-9 Mk. I (voice) / Nucleus (voice)
John Leeson
Lowe
Michael Sheard
Safran
Brian Grellis
Silvey
Jay Neill
Meeker
Edmund Pegge
Professor Marius
Frederick Jaeger
Original Music Composer
Dudley Simpson
Script Editor
Robert Holmes
Director
Derrick Goodwin
Writer
Dave Martin
Bob Baker
Producer
Graham Williams