Ainmere (d. 569), son of Sétnae and putatively king of Tara, belonged to the Cenél Conaill dynasty of Uí Néill. His father Sétnae is credited with six sons, but none of the others achieved any distinction. According to the ‘Banshenchas’ (lore of women), Ainmere married Brigit, daughter of Cobthach son of Ailill, king of Ard Ladrann, the caput of which was located at a site identified as the ‘moat of Ardamine’ (townland of Middletown, parish of Ardamine, Co. Wexford); she was the mother of his son Áed (qv). Ainmere comes to notice at the battle of Sligo in 547, when he assisted the Cenél nÉogain dynasts Forggus and Domnall sons of Muirchertach/Mac Ercae (qv), who are said to have shared the kingship of Tara, in slaying Éogan Bél (qv), king of Connacht. In 561 conflict within the Uí Néill dynasties involved Ainmere in the battle of Cúl Dreimne (near Drumcliff, Co. Sligo) along with Forggus, Domnall, and Áed Abrat (qv) son of Eochu Tírmchárna, against the king of Tara, Diarmait (qv) son of Cerball. Tradition has it that this Northern Uí Néill onslaught was prompted by St Colum Cille (qv). Ainmere's role in the battle of Móin Dairi Lothair two years later is noted by the saint's biographer Adomnán (qv).
Middle Irish king-lists imply that Ainmere succeeded to the kingship of Tara on the death of the two Cenél nÉogain brothers in 566, and accord him a reign of three years. He is not featured in ‘Baile Chuinn’. He may, in any event, have headed Uí Néill at this time. He was slain (569) by Fergus son of Néillíne, one of the Cenél nÉogain. Ainmere's immediate successor within Uí Néill was the Cenél nÉogain dynast Báetán (qv) son of Muirchertach/ Mac Ercae. His son Áed is said to have later reigned as king of Tara.