Tyndareus was a king of Sparta in Greek mythology, son of Oebalus and Gorgophone. He was the husband of Leda, with whom he had a number of children, including Castor, Clytemnestra, Timandra, Phoebe and Philonoe. Castor had a twin brother named Pollux, and Clytemnestra had a twin sister named Helen, better known as Helen of Troy; however, the father of Pollux and Helen was Zeus and not Tyndareus, as the god appeared in the form of a swan in front of Leda, and consummated with her on the same night that she was impregnated by Tyndareus.
Tyndareus was exiled by his brother Hippocoon, who took the throne of Sparta by force; Heracles later helped Tyndareus reclaim the throne and killed the usurper and his sons. Tyndareus welcomed the brothers Agamemnon and Menelaus who had been exiled by Thyestes from Mycenae; Agamemnon eventually married Clytemnestra, while Menelaus married Helen. All of them played important parts in the events that preceded and followed the Trojan War.