Ariston of Sparta in Wikipedia

Ariston (Ἀρίστων) was a king of Sparta, 14th of the Eurypontids, son of Agesicles, contemporary of Anaxandrides. He ascended the Spartan throne before 560 BC, and died somewhat before (Paus. iii. 7), or at any rate not long after, 510 BC. He thus reigned about 50 years, and was of high reputation, of which the public prayer for a son for him, when the house of Procles had other representatives, is a testimony. Demaratus, hence named, was borne him, after two barren marriages, by a third wife, whom he obtained, it is said, by a fraud from her husband, his friend, Agetus. (Herod. i. 65, vi. 61-66; Paus. iii. 7.§7; Plut. Apophth. Lac.)