The Tuatha Dé Danann ("peoples of the goddess Danu", Modern Irish pronunciation: [t̪ˠuːəhə dʲeː d̪ˠan̪ˠən̪ˠ], Old Irish: [tuːaθa ðʲeː ðaNaN]) are a race of people in Irish mythology. In the invasions tradition which begins with the Lebor Gabála Érenn, they are the fifth group to settle Ireland, conquering the island from the Fir Bolg.
The Tuatha Dé Danann are thought to derive from the pre-Christian deities of Ireland. When the surviving stories were written, Ireland had been Christian for centuries, and the Tuatha Dé were represented as mortal kings, queens and heroes of the distant past; however there are many clues to their former divine status. A poem in the Book of Leinster lists many of the Tuatha Dé, but ends "Although [the author] enumerates them, he does not worship them." Goibniu, Creidhne and Luchta are referred to as Trí Dé Dána ("three gods of craftsmanship"), and the Dagda's name is interpreted in medieval texts as "the good god." Even after they are displaced as the rulers of Ireland, characters such as Lugh, the Morrígan, Aengus and Manannán mac Lir appear in stories set centuries later, showing all the signs of immortality. They also have many parallels across the Celtic world: Nuada is cognate with the British god Nodens; Lugh is a reflex of the pan-Celtic deity Lugus; Tuireann is related to the Gaulish Taranis; Ogma to Ogmios; the Badb to Catubodua.
The translation of Tuatha Dé Danann as "peoples of the goddess Danu" is necessarily imprecise. Old Irish tuath (plural tuatha) means "people, tribe, nation"; and dé is the genitive case of día, "god, goddess, supernatural being, object of worship" (they are often referred to simply as the Tuatha Dé, a phrase also used to refer to the Israelites in early Irish Christian texts).
Danann is also a genitive, for which the nominative case is not attested. It has been reconstructed as Danu, which by analogy with Anu is taken to be a female name. The name of the river Danube is believed to be Celtic in origin, and Celtic river deities are usually female; Hindu mythology has a goddess called Danu, who may be an Indo-European parallel. However, this reconstruction is not universally accepted. It is also written Donann and Domnann, which may link them with the Fir Domnann ("men of the Domnainn"), a people associated with the Fir Bolg in myth, who are historically attested in Connacht and may be related to the British Dumnonii.
The Danaan Greeks of Homer's Iliad are not connected to the Tuatha Dé Danann. The spelling "Danaan" is a Latinate anglicisation of the Greek Δαναοί (Danaoi) and its similarity to "Danann" is coincidental.
The Tuatha Dé Danann were descended from Nemed, leader of a previous wave of inhabitants of Ireland. They came from four northern cities, Falias, Gorias, Murias and Finias, where they acquired their occult skills and attributes. They arrived in Ireland, on or about May 1 (the date of the festival of Bealtaine), on dark clouds, although later versions rationalise this by saying they burned their ships to prevent retreat, and the "clouds" were the smoke produced.
Led by their king, Nuada, they fought the First Battle of Magh Tuiredh (Moytura), on the west coast, in which they defeated and displaced the native Fir Bolg, who then inhabited Ireland. In the battle, Nuada lost an arm to their champion, Sreng. Since Nuada was no longer "unblemished", he could not continue as king and was replaced by the half-Fomorian Bres, who turned out to be a tyrant. The physician Dian Cecht replaced Nuada's arm with a working silver one and he was reinstated as king. However, Dian Cecht's son Miach was dissatisfied with the replacement so he recited the spell, "ault fri halt dí ⁊ féith fri féth" (joint to joint of it and sinew to sinew), which caused flesh to grow over the silver prosthesis over the course of nine days and nights. However, in a fit of jealous rage Dian Cecht slew his own son. Because of Nuada's restoration as leader, Bres complained to his family and his father, Balor, king of the Fomorians.
The Tuatha Dé Danann then fought the Second Battle of Magh Tuiredh against the Fomorians. Nuada was killed by the Fomorian king Balor's poisonous eye, but Balor was killed himself by Lugh, the champion of the Tuatha Dé, who then took over as king.
A third battle was fought against a subsequent wave of invaders, the Milesians, from the northwest of the Iberian Peninsula (present day Galicia and Northern Portugal), descendants of Míl Espáine (who are thought to represent the Goidelic Celts). The Milesians encountered three goddesses of the Tuatha Dé Danann, Ériu, Banba and Fodla, who asked that the island be named after them; Ériu is the origin of the modern name Éire, and Banba and Fodla are still sometimes used as poetic names for Ireland.
Their three husbands, Mac Cuill, Mac Cecht and Mac Gréine, who were kings of the Tuatha Dé Danann at that time, asked for a truce of three days, during which the Milesians would lie at anchor nine waves' distance from the shore. The Milesians complied, but the Tuatha Dé Danann created a magical storm in an attempt to drive them away. The Milesian poet Amergin calmed the sea with his verse, then his people landed and defeated the Tuatha Dé Danann at Tailtiu. When Amergin was called upon to divide the land between the Tuatha Dé Danann and his own people, he cleverly allotted the portion above ground to the Milesians and the portion underground to the Tuatha Dé Danann. The Tuatha Dé Danann were led underground into the Sidhe mounds by The Dagda.