Peter Davison
The Doctor
Acting
Sarah Sutton
Nyssa
Acting
Janet Fielding
Tegan Jovanka
Acting
Mark Strickson
Vislor Turlough
Acting
Nicholas Courtney
Brigadier Alistair Gordon Lethbridge-Stewart
Acting
Valentine Dyall
The Black Guardian
Acting
David Collings
Mawdryn
Acting
Angus MacKay
Headmaster
Acting
Stephen Garlick
Ibbotson
Acting
Roger Hammond
Dr. Runciman
Acting
Sheila Gill
Matron
Acting
Peter Walmsley
Mutant
Acting
Brian Darnley
Mutant
Acting