Conrad Veidt
— Otto Becker / Baron Hugo von Detner
Ann Ayars
— Kaaren De Relle
Frank Reicher
— Fritz
Dorothy Tree
— Miss Harper
Ivan F. Simpson
— Professor Sterling (as Ivan Simpson)
William Tannen
— Ludwig
Martin Kosleck
— Kurt Richten
Marc Lawrence
— Joe Aiello
Sidney Blackmer
— Arnold Milbar
Moroni Olsen
— Brenner
Pierre Watkin
— Grover Blaine McHenry
Ernie Alexander
— Sailor (uncredited)
Rudolph Anders
— Cab Driver (uncredited)
Jessie Arnold
— Landlady (uncredited)
Walter Bacon
— Spy (uncredited)
Polly Bailey
— Fat Woman (uncredited)
Roy Barcroft
— Chief Petty Officer (uncredited)
Barbara Bedford
— Woman (uncredited)
Arthur Belasco
— Detective (uncredited)
Walter Byron
— Officer (uncredited)
Baldwin Cooke
— Waiter (uncredited)
Hal Cooke
— Clerk (uncredited)
Clyde Courtright
— Doorman (uncredited)
Stuart Crawford
— Commentator (voice) (uncredited)
Jack Daley
— Reporter (uncredited)
Mark Daniels
— Cab Driver (uncredited)
Cliff Danielson
— Youth (uncredited)
Jack Deery
— Diplomat (uncredited)
Drew Demorest
— Reporter (uncredited)
Harry Denny
— Restaurant Patron (uncredited)