Manannán is a given name of Irish origin, deeply rooted in Irish mythology. It ultimately derives from the name of the Isle of Man, which may come from the Celtic root *moniyo- meaning "mountain." In Gaelic mythology, Manannán mac Lir is a powerful sea god and one of the Tuatha Dé Danann, the supernatural race of Irish legend.
Etymology
The name Manannán is thought to be derived from the Isle of Man, known as Manann or Mannin in Irish. The Celtic root *moniyo- (meaning "mountain") likely underlies both the island's name and the god's name, reflecting his association with the majestic landscape.
Mythological Significance
Manannán mac Lir (where mac Lir means "son of the Sea") is a central figure in Gaelic myth, appearing in Irish, Manx, and Scottish folklore. He is a god of the sea, a warrior, and a king of the otherworld. His domain is known by several evocative names: Emain Ablach ("Isle of Apple Trees"), Mag Mell ("Plain of Delights"), and Tír Tairngire ("Land of Promise"). He is described as the over-king of the surviving Tuatha Dé Danann after the arrival of humans (the Milesians) and uses the féth fíada (a mist of invisibility) to conceal his own home and the sidhe dwellings of his people.
Manannán is credited with owning magical items of immense power: a self-navigating boat called Sguaba Tuinne ("Wave-sweeper"), a horse named Aonbharr ("Single Mane") that can travel over sea and land, and a deadly sword named Fragarach ("Answerer" or "Retaliator"), which can cut through any armor and compels its victims to answer truthfully.
Comparisons and Variants
The Welsh mythological figure Manawydan (son of Llyr) is related to Manannán, both being derived from the Celtic god Mana. Manawydan appears in the Mabinogion as a wise and resourceful hero. The name Manannán itself remains in use as a given name, particularly in Ireland and among those interested in Gaelic heritage.
Sources: Wikipedia — Manannán mac Lir