Stewart Granger as Rudolf Rassendyll/King Rudolf V; Deborah Kerr as Princess Flavia; Louis Calhern as Col. Zapt; Jane Greer as Antoinette de Mauban; Lewis Stone as The Cardinal; Robert Douglas as Michael, Duke of Strelsau; Robert Coote as Fritz von Tarlenheim; Peter Brocco as Johann; Francis Pierlot as Josef; James Mason as Rupert of Hentzau; Ronald Colman as King Rudolf V; Madeleine Carrol as Princess Flavia