Atys (Greek: ) was the son of Croesus king of Lydia. He had one son named Pythius.
According to book one of the Histories by Herodotus, his father had a dream, in this dream he saw his son Atys being killed by a spear. As a result Croesus, seeking to prevent or stave off the foreseen fate, had his son married immediately and ceased sending him out to war. One day a giant boar began terrorizing Mysian Olympus, and the Mysians sent to Croesus seeking his son and a team of chosen young men and hounds to help drive it off. Croesus initially refused, but Atys talked his father into letting him hunt the boar, since boars don't wield iron weapons. Croesus gave his consent, but he sent Adrastus with him as a body guard. During the hunt, Adrastus accidentally killed Atys when hurling a spear at the boar. Riddled with guilt, Adrastus slew himself over the tomb of Atys.