In Greek mythology, Leucothea (//; Greek: Λευκοθέα, translit. Leukothéa, lit. "white goddess"), sometimes also called Leucothoe (Greek: Λευκοθόη, translit. Leukothóē), 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.
She has a sanctuary in Laconia, where she answers people's questions about dreams, her form of oracle.
In the version sited at Rhodes, a much earlier mythic level is reflected in the genealogy: There, a nymph or goddess named Halia ("salty")[a] plunged into the sea and became Leucothea. Her parents were the titans 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; their sons were maddened by Aphrodite in retaliation for an inhospitable affront, assaulted their own mother Halia, and were confined in caves beneath the island by their father Poseidon; Halia cast herself into the sea, and became Leucothea. The people of Rhodes traced their mythic descent from the nymph Rhodos and the Sun god Helios.
In the Odyssey, Leucothea makes a dramatic appearance and tells the shipwrecked Odysseus to discard his cloak and raft, and offers him a veil[b] to wind round himself, to save his life and reach land. Homer makes Leucothea the transfiguration of Ino.
It is possible that Leucothea is the "Leucothoe" that Hyginus makes the mother of Thersanon by Helios, although he could be referring to another woman by the same name.
To re-salute the world with sacred light,
As the sea-gull Κάδμου θυγάτηρ said to Odysseus
"get rid of parap[h]ernalia"