Neleus was a demigod and a son of Poseidon.
Neleus was the son of Poseidon and Tyro and brother of Pelias. He later married Cretheus, and had three sons with her: Aeson, Pheres, and Amythaon, though she loved Enipeus, a river god. She pursued Enipeus, who refused her advances.
One day, Poseidon, filled with lust for Tyro, disguised himself as Enipeus. From their union were born Pelias and Neleus, twin boys. Tyro exposed her sons on a mountain, but they were found and raised by a maid.
When they reached adulthood, Pelias and Neleus found their mother Tyro and then killed her stepmother, Sidero, for having mistreated her. Sidero tried to hide in a temple to Hera but Pelias killed her anyway, earning himself Hera's undying hatred. Neleus and Pelias then fought for the crown, and Neleus was banished to Messenia, becoming King of Pylos.
With Chloris, Neleus was the father of Pero, Periclymenus, Alastor and Nestor. Heracles later asked Neleus to cleanse him of a blood-debt, but was refused and killed Neleus and his sons, except for Nestor.