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

Dave Martin

Writer

Derrick Goodwin

Director

Bob Baker

Writer

Dudley Simpson

Original Music Composer

Graham Williams

Producer

Robert Holmes

Script Editor

Delia Derbyshire

Theme Song Performance