Vincent Price as Paul Toombes

Peter Cushing as Herbert Flay

Robert Quarry as Oliver Quayle

Adrienne Corri as Faye

Linda Hayden as Elizabeth Peters

Natasha Pyne as Julia Wilson

Michael Parkinson as TV Interviewer

Barry Dennen as Gerry Blount

Ellis Dayle as Alfred Peters (as Ellis Dale)

Catherine Willmer as Louise Peters

Jenny Lee Wright as Carol Clayton

Julie Crosthwaite as Ellen

John Garrie as Inspector Harper

Ian Thompson as Bradshaw

Peter Halliday as Psychiatrist

Basil Rathbone as Basil (archive footage)

Boris Karloff as (archive footage)

Hyma Beckley as Passenger on Quayside (uncredited)

George Blackler as George the Make-Up Artist (uncredited)

Robert Cawdron as CID Inspector (uncredited)

Michael Craze as Reporter (uncredited)

David Jackson as Police Sergeant (uncredited)

Patrick Jordan as Ship's Steward (uncredited)

Earl Rhodes as Boy Fishing (uncredited)

Pam Rose as Pretty Blonde (uncredited)

Christopher Sandford as Reporter (uncredited)

Reg Thomason as Hollywood Party Guest (uncredited)