Saint Mac NisseMac Nissi, Macnise, Macnissi; also in Latin, Macanisius, Macnisius. (died 514) was an early Irish saint known as the founder and first bishop-abbot of Connor (Irish: Condere, in what is now Co. Antrim).
Life Hagiographers say he was son of Fáebrach, son of Erc, who probably belonged to the Dál Fiatach.Breen, Aidan. "Mac Nisse", Dictionary of Irish Biography, October 2009 His mother was Ness.
His story as known is largely legendarySt. Angus MacNisse - Saints & Angels - Catholic Online He was baptized by Saint Patrick who taught him the psalms.Duffy, Patrick. "Sep 4 – St Mac Nissi (died c. 514) monk and bishop", Catholic Ireland, September 4, 2012 He then took the additional name of Óengus. Mac Nisse was fostered with Patrick's disciple Olcán, Bishop of Armoy. The Tripartite Life of St. Patrick says that as the political support of Dal Riata gained in Scotland, but waned in Ireland, the lands attached to Armoy were seized and regranted to Mac Nisse and Senán "of Inis Cathaig" (probably for Senán of Láthrach Briúin).Charles-Edwards, "Ulster, saints of (act. c.400–c.650)"
Oengus Mac Nisse is thought to have been a hermit near Kells earlier in his life.Simms, George Otto. Among the Cloud of Witnesses: Notes and suggested prayers for commemorations of worthies of the Irish Church, Church of Ireland, 1994
There were three Irish abbeys/monasteries by this name.
References
Primary sources Tripartite Life of St Patrick Félire Óengusso Annals of Ulster Life of St. Nisse (Codex Salmanticensis), ed. W.W. Heist, Vitae Sanctorum Hiberniae ex codice olim Salmanticensi nunc Bruxellensi. Brussels, 1965. p. 406. Short, late homily for the saint's festival (3 September) at Connor.