Lugh or Lug (; modern Irish: Lú ) is an important god of Irish mythology. A member of the Tuatha Dé Danann, Lugh is portrayed as a youthful warrior hero, a king and saviour. He is associated with skill, crafts and the arts as well as with oaths, truth and the law. He is sometimes interpreted as a sun god, a storm god or a sky god. Lugh is also strongly associated with the harvest festival of Lughnasadh, which is named after him.
Lugh is known by the epithets Lámfada (, meaning "long arm" or "long hand"), possibly for his skill with a spear or sling, Ildánach ("skilled in many arts"), Samildánach ("equally skilled in many arts"), Lonnbéimnech ("fierce striker"), Macnia ("youthful warrior/hero") and Conmac ("hound-son"). As to ancestry, Lugh is given the matrinamemac Ethlenn or mac Ethnenn ("son of Ethliu or Ethniu", his mother) and the patrinamemac Cein ("son of Cian", his father). He is the maternal grandson of the Fomorian, Balor, whom Lugh kills in the Battle of Mag Tuired. His foster-father is the sea god Manannán. Lugh's son is the hero Cú Chulainn, who is believed to be an incarnation of Lugh.
Lugh has several magical possessions. He wields an unstoppable fiery spear, a sling stone, and a sword named Fragarach ("the answerer"). He also owns a self-sailing boat named Scuabtuinne ("wave sweeper"), a horse named Enbarr, and a hound named Failinis.
He is a reflex of the pan- Celtic god Lugus, and his Welsh counterpart is Lleu Llaw Gyffes, "The Bright One with the Strong Hand".