All the Spartans and Thespians died, including Leonidas, whose corpse the Persians mangled. Herodotus says the Thebans, who had never wanted to be there, surrendered when Leonidas was killed.
Leonidas was the half-brother of the late King Cleomenes I of Sparta. After Cleomenes' probable suicide, Leonidas was made king because Cleomenes had died without a son or another, closer male relative to reign as his successor. There was another tie: Leonidas was also married to Cleomenes' only child and heir, the wise Gorgo. Herodotus says this was part of the reason he became king. Sparta had two hereditary kings at a time. One group was the Agiad and the other, the Eurypontid. As kings from the Agiad line, both Cleomenes and Leonidas claimed Heracles (Hercules) as ancestor.