Ailill Molt (‘ram[-like]’) (d. 482), son of Nath Í, king of Connacht and putatively king of Tara, was an early representative of the Uí Fhiachrach dynasty of Connacht. His father, Nath Í son of Fiachra, is claimed by Middle Irish sources to have been king of Tara. His mother is said to have been Eithne, daughter of Conrí Cas. According to the ‘Banshenchas’ (lore of women), Ailill married Uchdelb, daughter of Óengus (qv) son of Nad-fraích, an ancestor figure of Éoganacht Chaisil. Uchdelb was the mother of his sons, Cellach and (Mac) Erc(ae). Ailill's grandfather, Fiachra, features in the genealogies as a brother of the illustrious Niall Noígiallach (qv), Niall of the Nine Hostages.
Tradition, as reflected in the historical tale ‘Echtra mac Echdach Mugmedóin’, had it that Fiachra's line would ‘pay but a fleeting visit to Tara’ – an allusion to the reigns of Ailill and Nath Í. Otherwise, political supremacy was a prerogative of the dynasties that claimed descent from Niall. Ailill is included in the Old Irish king-list ‘Baile Chuinn’. The Annals of Ulster, citing the Book of Cuanu, state that Ailill Molt celebrated the Feis Temro (feast of Tara) in 467. This source also refers to battles at Dumae Achir (somewhere in Leinster) in 468, where Ailill was defeated by the Leinstermen, and at Cruachán Breg Éile (Croghan Hill, barony of Lower Philipstown, Co. Offaly) in 475, when he took his revenge on his Leinster enemies. The location of these battles within Leinster, which does not fit the geographical pattern of fifth–sixth century Uí Néill–Laigin conflict, and the placement of Ailill in the king-list between Lóegaire (qv) son of Niall and Lugaid, casts some doubt on the historicity of his kingship of Tara. His inclusion may reflect a perceived need on the part of Uí Néill interests, in the late seventh century, to retain the support of Uí Fhiachrach.
The account of Ailill's death at the battle of Ochae (Faughan Hill, near Navan, Co. Meath), placed at 482, is significant. According to the annalists, he was defeated by Lugaid son of Lóegaire and Muircheretach/Mac Ercae (qv), both of whom are assigned to the Uí Néill. Later sources also place the Laigin and the Ulaid at this battle, which (if true) represents a remarkable confederation against an isolated Ailill. Perhaps these embellished accounts reflect the range of dynastic interests that still aspired to the kingship of Tara in the fifth (and sixth) century. His son Mac Ercae was slain by the Leinstermen in 543 or 548; his grandson, Éogan Bél (qv) reigned as overking of Connacht from 502 to c.543.