Peter van Eyck as Henry B. Travers

Gert Fröbe as Detective Inspector Kras

Wolfgang Preiss as Prof. Jordan / Peter Cornelius / Dr. Mabuse

Dawn Addams as Marion Menil

Werner Peters as Hieronymus B. Mistelzweig

Andrea Checchi as Hotel Detective Berg

Howard Vernon as No. 12

David Cameron as Michael Parker

Christiane Maybach as Maid

Albert Bessler as Hotelingenieur

Marielouise Nagel as The Blonde Luck

Reinhard Kolldehoff as Roberto Menil aka 'Klumpfuß'

Nico Pepe as Hotel-Manager

Jean-Jacques Delbo as Cornelius' Butler

Linda Sini as Corinna

Renate Küster as TV announcer

Rolf Weih as Interpol-Chef

Rolf Moebius as Police-Officer

Maria Milde as Chambermaid

Dieter Hallervorden as Photojournalist (uncredited)

Bruno W. Pantel as Reporter (uncredited)

Wolfgang Völz as Barkeeper Karl (uncredited)

Werner Buttler as No. 11 (uncredited)

Hans W. Hamacher as BKA-Chef (uncredited)

Egon Vogel as Police doctor (uncredited)