Major Tuatha Dé Danann deity — sea-god, lord of the Otherworld, over-king of the Tuath Dé after the Milesian conquest. His domain is the sea-as-otherworld-passage. Wields the Sguaba Tuinne (self-navigating boat), Aonbharr (water-traversing horse), Fragarach (truth-compelling sword), and the féth fíada (cloak of mists). The Isle of Man bears his name and preserves continuous folk-cult (the Midsummer rent-paying ritual). Lord of Emain Ablach (Avalon-cognate), Mag Mell, and Tír Tairngire. Foster-father of Lugh and other Tuatha Dé children. Father of Mongán mac Fíachnai (the historical Dál nAraide king d. c. 625) by Caintigern in the bargain-with-Fíachna tradition recorded in Compert Mongáin.