as David Mendelssohn
as Dr. Robert Cook
as Cornelius A. Woaegen, president of GTI
as Benson Thacker
as French-Canadian Radio Speaker (voice) (uncredited)
as Harvey Wood
as Dr. Jekyll & Mr. Hyde (uncredited)
as Prince Andrei Bolkonsky
as Professor Carter
as Robert Cohn
as Maj. Gen. Robert Haines
as Noel, Marquis de Maynes
as Mel Fields
as Radcliffe (US version)
as Frenchy Fairmont
