The greatness of Manannan mac Lir, “son of the sea,” is proved by the fact that he appears in many of the heroic tales, and is still remembered in tradition and folk-tale.  He is a sea-god who has become more prominent than the older god of the sea, and though not a supreme god, he must have had a far-spreading cult.  With Bodb Dearg he was elected king of the Tuatha De Danann.  He made the gods invisible and immortal, gave them magical food, and assisted Oengus in driving out Elemar from his sid.  Later tradition spoke of four Manannans, probably local forms of the god, as is suggested by the fact that the true name of one of them is said to be Orbsen, son of Allot.  Another, the son of Ler, is described as a renowned trader who dwelt in the Isle of Man, the best of pilots, weather-wise, and able to transform himself as he pleased.  The Coir Anmann adds that the Britons and the men of Erin deemed him god of the sea.[305] That position is plainly seen in many tales, e.g. in the magnificent passage of The Voyage of Bran, where he suddenly sweeps into sight, riding in a chariot across the waves from the Land of Promise; or in the tale of Cuchulainn’s Sickness, where his wife Fand sees him, “the horseman of the crested sea,” coming across the waves.  In the Agallamh na Senorach he appears as a cavalier breasting the waves.  “For the space of nine waves he would be submerged in the sea, but would rise on the crest of the tenth without wetting chest or breast."[306] In one archaic tale he is identified with a great sea wave which swept away Tuag, while the waves are sometimes called “the son of Lir’s horses”—­a name still current in Ireland, or, again, “the locks of Manannan’s wife."[307] His position as god of the sea may have given rise to the belief that he was ruler of the oversea Elysium, and, later, of the other-world as a magical domain coterminous with this earth.  He is still remembered in the Isle of Man, which may owe its name to him, and which, like many another island, was regarded by the Goidels as the island Elysium under its name of Isle of Falga.  He is also the Manawyddan of Welsh story.

Manannan appears in the Cuchulainn and Fionn cycles, usually as a ruler of the Other-world.  His wife Fand was Cuchulainn’s mistress, Diarmaid was his pupil in fairyland, and Cormac was his guest there.  Even in Christian times surviving pagan beliefs caused legend to be busy with his name.  King Fiachna was fighting the Scots and in great danger, when a stranger appeared to his wife and announced that he would save her husband’s life if she would consent to abandon herself to him.  She reluctantly agreed, and the child of the amour was the seventh-century King Mongan, of whom the annalist says, “every one knows that his real father was Manannan."[308] Mongan was also believed to be a rebirth of Fionn.  Manannan is still remembered in folk-tradition, and in the Isle of Man, where his grave is to be seen,