A hero of Locri in Italy, was a son of Astycles or of the river-god Caecinus. He was famous for his strength and skill in boxing, and delivered the town of Temessa from the evil spirit Polites, to whom a fair maiden was sacrificed every year. Euthymus himself disappeared at an advanced age in the river Caecinus. (Strab. vi. p. 255; Aelian, V. H. viii. 18 ; Eustath. ad Hom. p. 1409.) He gained several victories at Olympia (0l. 74, 76, and 77); and a statue of his at Olympia was the work of Pythagoras. (Paus. vi. 6. § 2, 10. § 2.)