Bela Lugosi
Dr. Feodor Orloff / Prof. John Dearborn
Hugh Williams
Det. Insp. Larry Holt
Greta Gynt
Diana Stuart
Edmon Ryan
Lieutenant Patrick O'Reilly
Wilfred Walter
Blind Jake
Arthur E. Owen
Dumb Lou
Alexander Field
Fred Grogan
Gerald Pring
Henry Stuart
O.B. Clarence
Prof. John Dearborn (voice)
May Hallatt
Police Constable Griggs
Bryan Herbert
Police Sgt. Walsh
Charles Penrose
Morrison, undercover detective
Julie Suedo
Orloff's Secretary