Achaeus was, according to nearly all traditions, a son of
Xuthus and
Creusa, and consequently a brother of
Ion and grandson of
Hellen. The
Achaeans regarded him as the author of their race, and derived from him their own name as well as that of Achaia, which was formerly called Aegialus. When his uncle
Aeolus in
Thessaly, whence he himself had come to
Peloponnesus, died, he went there and made himself master of
Phthiotis, which now also received from him the name of Achaia.
Servius alone calls Achaeus a son of
Jupiter (
Zeus) and Pithia, which is probably miswritten for Phthia, compare the account of
Clement.