(Ἰαπετός), a son of Uranus and Ge, a Titan and brother of Cronus, Oceanus, Coeus, Hyperion, Tethys, Rhea, &c. (Apollod. 1.1.3; Diod. 5.66.) According to Apollodorus (1.2.3) he married Asia, the daughter of his brother Oceanus, and became by her the father of Atlas, Prometheus, Epimetheus, and Menoetius, who was slain by Zeus in the war against the Titans, and shut up in Tartarus. Other traditions call the wife of Iapetus Clymene, who was likewise a daughter of Oceanus, and others again Tethys, Asopis, or Libya. (Hes. Th. 507, &c.; Tzetz. ad Lycoph. 1277; Orph. Fragm. 8.21, &c.; Verg. G. 1.279.) Hyginus, who confounds the Titans and Gigantes, makes Iapetus a Giant, and calls him a son of Tartarus. According to Homer (Hom. Il. 8.479) Iapetus is imprisoned with Cronus in Tartarus, and Silius Italicus (12.148, &c.) relates that he is buried under the island of Inarime. Being the father of Prometheus, he was regarded by the Greeks as the ancestor of the human race. His descendants, Prometheus, Atlas, and others, are often designated by the patronymic forms Iapelidae (es), Iapetionidae (es), and the feminine Iapetionis. (Hes. Th. 528; Ov. Met. 4.631; Pind. O. 9.59; comp. Voelcker, Mytholog. des Japetischen Geschlechtes, p. 4, &c.) Another mythical personage of the same name, the father of Buphagus, is mentioned by Pausanias (8.27.11).
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890