After 300: The Posthumous Vengeance of King Leonidas of Sparta
Mythologically descended from the hero Herakles, the Agiad dynasty of ancient Sparta reigned alongside the Eurypontids almost since the beginning of the city-state. When war was on the borders of their land, and that of their neighboring city-states, it was to the current Heraklean descendent that those city-states turned.
Source: ancient-origins.net