First Milesian (i.e. Goidelic) king of Ireland, who established his capital at Tara, according to the pseudo-history Lebor Gabála[Book of Invasions]. As one of the two most important sons, with Eber Finn, of Míl Espáine, Éremón takes a leading role in the Milesian conquest of Ireland, distinguishing himself in a defeat of the Tuatha Dé Danann at Tailtiu, as described in Altrom Tige Dá Medar. In victory, however, he enters into a dispute with his brother and ally, Eber Finn. The poet Amairgin arbitrates the division of Ireland between the brothers, choosing a border following the Eiscir Riada, a ridge of mounds between Galway Bay and Dublin; Eber takes the south with six chiefs and Éremón the north and seven chiefs. Unhappy with this settlement, Eber attacks Éremón but is killed by him. This leaves Éremón as the sole ruler of a united island, but the feud is thought to have been continued by their descendants. Éremón establishes his capital at the hill of Temair (see TARA), named for his wife Téa.
Perhaps because Éremón was cited in so many pedigrees and genealogies, the name, under different spellings, was borne by some later petty kings and noblemen. Éremón's uniting of the island led to his being compared to King David of Judea by exegetical medieval commentators. But modern commentators, especially those influenced by Georges Dumézil (1898–1986), find it more significant that Éremón, representing the north, acquires the whole island and the kingship.
See Georges Dumézil, Le Troisième Souverain (Paris, 1949), 167–86.