In Greek mythology, the Golden Fleece (Greek: Χρυσόμαλλον Δέρας; Georgian: ოქროს საწმისი) is the fleece of the gold-hair winged ram, which can be procured in Colchis. It figures in the tale of Jason and his band of Argonauts, who set out on a quest by order of King Pelias for the fleece in order to place Jason rightfully on the throne of Iolcus in Thessaly. The story is of great antiquity – it was current in the time of Homer (eighth century BC) – and, consequently, it survives in various forms, among which details vary. Thus, in later versions of the story, the ram is said to have been the offspring of the sea god Poseidon and Themisto (less often, Nephele or Theophane). The classic telling is the Argonautica of Apollonius of Rhodes, composed in mid-third century BC Alexandria, recasting early sources that have not survived. Another, much less-known Argonautica, using the same body of myth, was composed in Latin by Valerius Flaccus during the time of Vespasian.

Athamas the Minyan, a founder of Halos in Thessaly but also king of the city of Orchomenus in Boeotia (a region of southeastern Greece), took as his first wife the cloud goddess Nephele, by whom he had two children, the boy Phrixus and the girl Helle. Later he became enamored of and married Ino, the daughter of Cadmus, bringing drought upon his land when Nephele removed herself. Ino was jealous of her stepchildren and plotted their deaths: in some versions, she persuaded Athamas that sacrificing Phrixus was the only way to end the drought. Nephele, or her spirit, appeared to the children with a winged ram whose fleece was of gold. The ram had been sired by Poseidon in his primitive ram-form upon a nymph, Theophane, the granddaughter of Helios, the sun-god. According to Hyginus, he carried her away to an island where he made her into an ewe so that he could have his way with her among the flocks, where Theophane's other suitors could not distinguish the ram-god and his consort.