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