In Irish mythology, Nuada, Nuadu (later Nuadha, Nuadhu, genitive Nuadat), known by the epithet Airgetlám ("Silver Hand"), was a king of the Tuatha Dé Danann. He is cognate with the Gaulish and British god Nodens. His Welsh equivalent is Nudd or Lludd Llaw Eraint.

One of the Four Treasures of the Tuatha Dé Danann was his sword, Fragarach, which cut his enemies in half (in other stories Fragarach is the Sword of Manannan mac Lir).

Nuada was king of the Tuatha Dé before they came to Ireland, but in the first Battle of Magh Tuiredh, in which they conquered Ireland from the Fir Bolg, Nuada had his arm cut off by the Fir Bolg warrior Sreng. Since he was no longer physically perfect he could not continue as king, and so the half-Fomorian Bres became the first Tuatha Dé Danann High King of Ireland.

Bres turned out to be a tyrant, enslaving the Tuatha Dé, forcing them to pay tribute to the Fomorians and neglecting his duties of hospitality. So Nuada had his arm replaced by a working one of silver by the physician Dian Cecht and the artificer Creidhne, and he was restored to the kingship, gaining his epithet Airgetlám ("silver hand"). Later, Dian Cecht's son, Miach, replaced the silver arm with an arm of flesh and blood; Dian Cecht killed him out of professional envy.

Nuada could not throw off the Fomorian yoke until the multi-talented Lug joined his court. He put Lug in command of the army, and he led them to victory against the Fomorians in the Second Battle of Magh Tuireadh, but Nuada was killed in the battle by Balor, the Fomorian leader.

He is probably the same figure as Elcmar, and possibly Nechtan.

Other characters of the same name include the later High Kings Nuadat Finnfail and Nuada Necht, and Nuada, the maternal grandfather of Fionn mac Cumhail. A rival to Conn of the Hundred Battles was Mug Nuadat ("Nuada's Slave"). The Delbhna, a people of early Ireland, had a branch called the Delbhna Nuadat who lived in County Roscommon.