[OIr. gobae, smith].
Smith of the Tuatha Dé Danann and one of the three gods of craft, na trídé dána, along with Credne and Luchta. Goibniu is seen most vividly in Cath Maige Tuired [The (Second) Battle of Mag Tuired], where he is a tireless armourer, providing Lug Lámfhota with the spear that penetrates Balor's eye. His keen tips are always lethal. T. F. O'Rahilly (1946) has argued, however, that as a god of thunder and lightning Goibniu may be identified with Balor, as both derive from a conception of the sun; the spear given to Lug may be derived from a thunderbolt. At times Goibniu was himself also a combatant. When the Fomorian spy Rúadán (2), the son of Bres (1) and Brigit, impaled Goibniu with one of his own spears, the smith took it from his body and dispatched the young man with it. This caused the mother, here known as Bríg[h], to wail the first keening heard in Ireland.
Genealogies disagree about Goibniu's lineage. He may be a grandson of the war-god Néit, as is Balor, and one of the four sons of Esarg, along with Credne, Luchta, and Dian Cécht, the healing god. In an alternate text he is the brother of the Dagda, Nuadu Airgetlám, Credne, and Luchta, with whom he helps to conquer Ireland for the Tuatha Dé Danann. In yet other texts Tuirbe Trágmar the axe-thrower, father of the Gobbán Saor, is named as Goibniu's father. Sometimes Goibniu is named as foster-father of Lug Lámfhota instead of Manannán mac Lir.
Along with his smithing, Goibniu was often seen as a healer; his name is invoked on an Old Irish charm to aid removal of a thorn. More significantly, he is host of an other-worldly feast, Fled Goibnenn, where guests imbibed great quantities of an intoxicating drink now identified with ale. Instead of getting drunk, those attending would be protected from old age and decay. Commentators see in this yet another link with Hephaestus, the Greek smith-god, who provides the other gods drink in the Iliad. Goibniu's forge, Cerdchae Ghaibhnenn, was usually thought to lie east of Mullaghmast hill in Glenn Treithim along the Kildare-Wicklow border. The once abundant copper ore in this area allowed early metalsmiths to make shields and spear-points. Other traditions place the forge on the Beare peninsula, Co. Cork, and elsewhere.
Much of Goibniu's characterization survives in the folk figure Gobbán Saor, with echoes also in Gaiblín, owner of the fabulous cow Glas Ghaibhleann. His Welsh counterparts are Gofannon and Glwyddyn Saer.
See Vernam Hull, ‘The Four Jewels of the Tuatha Dé Danann’, Zeitschrift für celtische Philologie, 18 (1930), 73–89.