A wise and gentle sea-god, a son of Pontus and Gaea. He is the father of the fifty Nereides by Doris. Nereus, known as the Old Man of the Sea, had the gift of prophecy and could change himself into any shape (Theogony 233-264). Heracles, seeking the location of garden of the Hesperides, asked Nereus for directions but he refused to help him. Heracles seized the god and held him fast and despite changing into many forms Nereus could not escape Heracles' powerful grip. Finally, Nereus relented and told the hero where to find the garden.
Nereus and Doris and their fifty daughters mainly dwelled in the depths of the Aegean sea. He had a temple near Trachin in Thessaly (Metamorphoses I, 177-198; XI, 346-409).