Lionel Barrymore
Professor Zelin
Elizabeth Allan
Irena Borotyn
Lionel Atwill
Inspector Neumann
Henry Wadsworth
Fedor Vincente
Holmes Herbert
Sir Karell Borotyn
Michael Visaroff
Innkeeper
Egon Brecher
Coroner (uncredited)
Robert Greig
Fat Man (uncredited)
John George
Gypsy (uncredited)
Louise Emmons
Old Gypsy Woman (uncredited)