 | Sal Ponti als Demetrios |
 | Joyce Taylor als Princess Antillia |
 | John Dall als Zaren |
 | William Smith als Captain of the Guard |
 | Edward Platt als Azor the High Priest |
 | Frank De Kova als Sonoy the Astrologer |
 | Berry Kroeger als Surgeon |
 | Edgar Stehli als King Kronas |
 | Wolfe Barzell als Petros, Demetrios' Father |
 | Jay Novello als Xandros the Greek Slave |
 | Paul Frees als Narrator / Multiple Voices (voice) |
 | Nestor Paiva als Megalos (uncredited) |
 | John Hart als Nobleman (uncredited) |
 | Phyllis Douglas als Girl (uncredited) |
 | I. Stanford Jolley als Governor of Rivers (uncredited) |
 | Gene Roth als Governor of Animals (uncredited) |
 | Charles Horvath als Nobleman (uncredited) |
| Charles Cirillo als Slave (uncredited) |
| George Bruggeman als Guard (uncredited) |
| Robert 'Big Buck' Maffei als Andex the Giant (uncredited) |
 | Byron Morrow als Governor of the Mountains (uncredited) |
| Will J. White als Officer (uncredited) |
| Ralph Smiley als Pavlo (uncredited) |
| Harry Fleer als Governor of Science (uncredited) |
| David Dyer als Priest (uncredited) |
| Alan Callow als Norseman Slave (uncredited) |
| George Pal | Director |
| George Pal | Producer |
| Daniel Mainwaring | Writer |
| Gerald Hargreaves | Theatre Play |
| Russell Garcia | Original Music Composer |
| Harold E. Wellman | Director of Photography |
| Ben Lewis | Editor |
| George W. Davis | Art Direction |
| William Ferrari | Art Direction |
| Henry Grace | Set Decoration |
| Richard Pefferle | Set Decoration |
| William Tuttle | Makeup Artist |
| Mary Keats | Hairstylist |
| Jim Danforth | Visual Effects |
| Wah Chang | Visual Effects |
| Gene Warren | Visual Effects |
| Lee LeBlanc | Special Effects |
| A. Arnold Gillespie | Special Effects |
| Robert R. Hoag | Special Effects |
| John Truwe | Makeup Artist |
| Franklin Milton | Recording Supervision |
| Charles Horvath | Stunts |
| Roy Jenson | Stunts |
| Paul Baxley | Stunts |
