- Richard Egan as Leonidas
- Ralph Richardson as Themistocles
- David Farrar as Xerxes
- Diane Baker as Ellas
- Barry Coe as Phylon
- Donald Houston as Dienekes
- Anna Synodinou as Gorgo
- John Crawford as Ephialtes
- Kieron Moore as Astinos
- Patrick Barr as Daxos
- Robert Brown as Messanger
- John Derek as Astinos' Son