Énnae Cennselach (5th cent.?), son of Labraid and putatively king of Leinster, was the eponymous ancestor of the south Leinster dynasty of Uí Chennselaig. A genealogical synchronism which makes Énnae coeval with Niall Noígiallach (qv), Dúnlaing (qv) son of Énnae Nia, and Nad-fraích (ancestor figures of the Uí Néill, Uí Dúnlainge, and Éoganacht of Cashel respectively), implies that all four flourished immediately prior to the introduction of Christianity. Contradictions in the genealogies, however, clearly betray contrivance. The Leinster kinglist assigns Énnae a lengthy reign of forty years, while a poem ascribed to a certain Anmchad credits the ancestor of Uí Chennselaig with twelve victories against the kings of Uí Néill, his last victory being over Lóegaire (qv).
An apparently late genealogical tradition assigns Énnae three brothers, Drón, Daigre, and Daig; these are eponymous ancestors of Uí Dróna, Uí Daigre, and Uí Dega. Other traditions represent Énnae as the father of Daig, while other alleged sons include Fedelmid (ancestor of Uí Fheilmeda) and Eochu the supposed slayer of Niall Noígiallach. Yet another son was Crimthann, who was believed to have been baptised by St Patrick (qv) and is credited with the grant of Sletty to Bishop Fiacc (qv). Énnae is said to have been slain by his grandson, Eochu Guinech, king of Uí Bairrche. Through his son Crimthann, whose death is placed under the year 483, he is the ancestor of all the later kings of Uí Chennselaig.