A master of many skills among the Tuatha Dé Danann, who slays the tyrant Balor.
Lugh ("the shining one") is a master of every skill among the Tuatha Dé Danann, and the god most directly responsible for Ireland's deliverance from Fomorian oppression. He is fostered in his youth by Manannán mac Lir in the Otherworld, and arrives at Nuada's court at Tara already accomplished in a remarkable range of crafts — carpentry, smithcraft, championship, harping, poetry, history, sorcery, and medicine among them.
The doorkeeper at Tara initially refuses him entry, since the hall already has a master of each individual skill and admits no one without a unique function. Lugh's answer becomes one of the most quoted lines in the tradition: he asks whether they have any one person who is master of all these skills at once — and when told no, he is admitted, earning the title Lugh Samildánach, "Lugh of the many talents." He is set a series of tests to prove his claims (including besting the Tuatha Dé Danann's champion at a board game) before being accepted, and eventually takes over command from Nuada for the Second Battle of Mag Tuired against the Fomorians.
Lugh's connection to the Fomorians is personal as well as political — his own grandfather is Balor, the Fomorian king whose single eye kills anything it looks upon, opened only when its heavy lid is lifted by a hook through it. In the climactic battle, Lugh kills Balor with a sling-stone through that eye, turning the weapon back on the very army it was meant to devastate. Lugh is also the father, in the Ulster Cycle, of Cú Chulainn, conceived with the mortal woman Deichtine — making Cú Chulainn's superhuman feats in that later cycle a direct inheritance from his divine father.
Tales of Fionn mac Cumhaill and his band of warriors, the Fianna, set generations after the Ulster Cycle in a world of hunting, romance, and roaming adventure.
No single domain — Lugh is defined by mastering every skill at once (carpentry, smithcraft, poetry, sorcery, and more), earning the title Lugh Samildánach, "Lugh of the many talents," rather than presiding over one craft.
How did Lugh kill Balor?
In the Second Battle of Mag Tuired, Lugh killed his own grandfather Balor — whose single deadly eye had to be lifted open by a hook through its heavy lid — with a sling-stone through that same eye, turning Balor's own weapon back on the Fomorian army.
Is Lugh the father of Cú Chulainn?
Yes — in the Ulster Cycle, Lugh fathers Cú Chulainn with the mortal woman Deichtine, making the hero's superhuman feats a direct inheritance from his divine father.