Son of Eurysthenes, founder of the royal house of the Agiadae (Pausanias iii. 2.1). His genealogy was traced through Aristodemus, Aristomachus, Cleodaeus and Hyllus to Heracles (Herodotus 7, 204), and he belongs rather to mythology than to history. Tradition ascribed to him the capture of the maritime town of Helos, which resisted his attempt to curtail its guaranteed rights, and the institution of the class of serfs called Helots.