Leonidas was a 5th century B.C. Spartan military king who bravely led a small force of Greeks -- mostly Spartan (the famous 300), but also Thespians and Thebans -- against the much larger Persian army of Xerxes, at the pass of Thermopylae, in 480 B.C. during the Persian Wars. According to Herodotus, Leonidas had been warned by the Delphic oracle that either Sparta would be destroyed or their king would lose his life. Leonidas chose the second alternative.