Áed mac Ainmuirech (died 598) was high-king of the Northern Uí Néill. He belonged to the Cenél Conaill and was a distant cousin of Columba of Iona. He was the son of Ainmuire mac Sétnai (died 569), a previous possible high king. His mother was Bríg, daughter of Chobtaig, son of Ailill, son of Nath Í, son of Crimthann mac Énnai son of Énnae Cennsalach of the Uí Ceinnselaig dynasty from Leinster.
He came to power some decades after the death of the last old, pagan style high-king of Tara, Diarmait mac Cerbaill (d. 565), after a period in which it is not clear that the Uí Néill had a high-king, nor is it certain that his contemporaries would have acknowledged Áed as such. The high kingship of Ireland rotated between the Cenél nEógain and Cenél Conaill branches in the late 6th century. It is difficult to disentangle the reign of Áed from that of his older second cousin Báetán mac Ninneda (died 586). Various lengths are given to the reign of Áed in the kinglists all of which would put the start of his reign before the death of Báetán. Both kings are omitted from the Baile Chuinn, the earliest Irish king list of the late 7th century, but this was probably a partisan document. It is possible that Báetán was not actually high king but was given this position by the synthetic historians to explain away the rule of Báetán mac Cairill (died 581) of the Dal Fiatach of Ulster as high king. The kinglists only assign him a reign of one year. Whether Báetán was king of Tara or not, the real effective power among the northern Ui Neill was Áed mac Ainmuirech.
He is known to have met with Áedán mac Gabráin, king of Dál Riata, in 575 at The Synod or Convention of Drumceat, to agree an alliance, presumably arranged by his cousin Columba. Áed and Áedán were both threatened by the activities Ulaid king Báetán mac Cairill of the Dál Fiatach, and it served both interests that Dál Riada not be subjected to the ambitious Báetán. In this they succeeded. Áed may have become high king after this possibly in 576. It is also quite possible that this conference did not take place until circa 587 which is the date recorded in the Annals of Clonmacnoise. The death of Báetán mac Ninneda had occurred in 586 and the Annals of Ulster record two death dates for Báetán mac Cairill, one being in 587.