| Richard Widmark | Michael Reynolds |
| Sonja Ziemann | Julia Jansci |
| Charles Regnier | The Count |
| Walter Rilia | Prof. Jansci |
| Howard Vernon | Col. Hidas |
| Senta Berger | Elsa |
| Heinz Moog | Minister Sakenov |
| Oskar Wegrostek | The fat man |
| Stefan Schnabel | Border official |
| Helmuth Janatsch | Janos |
| John Horsley | Jon Bainbridge |
| Raul Retzer | Special Agent |
| Adi Berber | Sandor |
| Jochen Brockmann | the Commandant |
| René Kolldehoff | Actor |
| Hubert VonMeyerinck | Hermann Sheffler |
| Elisabeth Neumann-Viertel | Olga |
Technical Credits
| Phil Karlson | Director |
| Leo Bei | Costumes/Costume Designer |
| Mutz Greenbaum | Cinematographer |
| Jean Hazelewood | Screenwriter |
| Alistair MacLean | Screenwriter |
| Rudolf Ohlschmiddt | Makeup |
| Werner Schlichting | Art Director |
| Isabella Schlichting | Art Director |
| Bob Simmons | Stunts |
| Aaron Stell | Editor |
| Richard Widmark | Producer |
| John Williams [composer] | Score Composer |