NEREUS Father of the Nereides, he was the ancient sea god, who ruled before Poseidon. Represented as an old man with a look of dignity, Nereus lost his dominion over the sea when the Earth was divided among Zeus, Hades and Poseidon, and the latter was alotted the kingdom of the deep, but Nereus obtained a position under Poseidon, and also the power of prophecy.