Theopompus (Greek: Θεόπομπος) was a Eurypontid king of Sparta. He is believed to have reigned during the late 8th and early 7th century BC. Sparta was a diarchy, having two kings at the same time, an Agiad and a Eurypontid. Theopompus was the son and successor to the Eurypontid king Nicander. The major event of his reign was the First Messenian War, which resulted in the defeat of the Messenians, for which, Pausanias reports, Tyrtaeus credits Theompompus: To our king beloved of the gods, Theopompus, through whom we took Messene with wide dancing-grounds.