The nereids were figures from Greek mythology, sea nymphs, daughters of Nereus and the oceanid Doris. (according to mythological tradition, the Oceanids were the daughters of the titans Oceanus and Tethys, his sister)
They were considered benevolent and immortal creatures, they were part of the marine thiasos of Poseidon together with the Tritons, depicted as beautiful young girls with pearls in their hair, usually close to dolphins and seahorses. The best known nereids, among the fifty or so mentioned in mythological literature, include Amphitrite, wife of Poseidon, Galatea, with whom the shepherd Acis fell in love, and Thetis, mother of Achilles.