Self (archive footage)
Patriarch
CIA Chief Frankenheimer
Judge Michael Lengel
Arthur Orloff
Carl Charnock
Stephan Mathiesen
Cornelius A. Woaegen
David Mendelssohn
General Murchison
Anthony Durano
Dr. Sanford
Professor Carter
Andreas Heggener
Sheriff
Joshua
Dr. Walker
Radcliffe (US version)
Vera's husband
Dr. Sidney Coleman
Self (archive footage) (uncredited)
Roberto Micheli
Colonel Stone
King Eurich
Dr. Robert Cook
Sheriff
Professor Henry Douglas
Peseti
Harvey Wood
Van Gould
Aurelio Morelli
Police superintendent
District Attorney Mannino
Mel Fields
Massimo Oderisi
Dalton Harvey
Doctor Harrison
French-Canadian Radio Speaker (voice) (uncredited)
El Greco (Domenico Teotocopulo)
Dr. Rudolph (Rudy) DeMeyer
Cleander
Dr. Jekyll & Mr. Hyde (uncredited)
Juan Bautista de La Salle
Maj. Gen. Robert Haines
Philip Allan
Andrea Di Tula
Stephen Orlac
Leopoldo De Karnstein
Benson Thacker
Maj. Foster MacLain
Robert Cohn
Giancarlo Barandero
Crown Prince Rudolph
Le comte Henri de Chevincourt
Prince Andrei Bolkonsky
Capt. Alfred Westerman
Don Paolo Salinas
Henrik
Paul Berthalet
Noel, Marquis de Maynes
Frenchy Fairmont
Luís Bello
Gabriel 'Gobby' Broome
Scott Mason Carter