(Ἄστακος).

1. A son of Poseidon and the nymph Olbia, from whom the town of Astacus in Bithynia, which was afterwards called Nicomedeia, derived its name. (Arrian. apud Steph. Byz. s. v.; Paus. 5.12.5; Strab. xii. p.563.)