In Greek mythology, Leucothea (Greek: Leukothea (Λευκοθέα), "white goddess") was one of the aspects under which an ancient sea goddess was recognized, in this case as a transformed nymph.
In the more familiar variant, Ino, the daughter of Cadmus, sister of Semele, and queen of Athamas, became a goddess after Hera drove her insane as a punishment for caring for the newborn Dionysus. She leapt into the sea with her son Melicertes in her arms, and out of pity, the Hellenes asserted, the Olympian gods turned them both into sea-gods, transforming Melicertes into Palaemon, the patron of the Isthmian games, and Ino into Leucothea.
In the version sited at Rhodes, a much earlier mythic level is reflected in the genealogy: there, the woman who plunged into the sea and became Leucothea was Halia ("of the sea", a personification of the saltiness of the sea) whose parents were from the ancient generation, Thalassa and Pontus or Uranus. She was a local nymph and one of the aboriginal Telchines of the island. Halia became Poseidon's wife and bore him Rhodos and six sons; the sons were maddened by Aphrodite in retaliation for an impious affront, assaulted their sister and were confined beneath the Earth by Poseidon. Thus the Rhodians traced their mythic descent from Rhodos and the Sun god Helios.
In the Odyssey (5.333 ff.) Leucothea makes a dramatic appearance as a gannet who tells the shipwrecked Odysseus to discard his cloak and raft and offers him a veil (κρήδεμνον, kredemnon) to wind round himself to save his life and reach land. Homer makes her the transfiguration of Ino. In Laconia, she has a sanctuary, where she answers people's questions about dreams. This is her form of the oracle.