Nereid, in Greek religion, any of the daughters (numbering 50 or 100) of the sea god Nereus (eldest son of Pontus, a personification of the sea) and of Doris, daughter of Oceanus (the god of the water encircling the flat Earth). The Nereids were depicted as young girls, inhabiting any water, salt or fresh, and as benign toward humanity. They were popular figures in Greek literature. The best known of the Nereids were Amphitrite, consort of Poseidon (a sea and earthquake god); Thetis, wife of Peleus (king of the Myrmidons) and mother of the hero Achilles; and Galatea, a Sicilian figure loved by the Cyclops Polyphemus.