Ua Brolcháin, Máel-Ísu (d. 1086), author and ecclesiastic, was a member of the Uí Brolcháin, which produced a number of important Armagh churchmen in the eleventh and twelfth centuries. According to John Colgan (qv), he was educated at the monastery of Both Chonais (in the parish of Culdaff, Co. Donegal). He became a cleric and teacher in Armagh and later coarb (successor to the founder) of the monastic church there. If we may judge by his poetry, he led a life marked by asceticism and strict devotion. At least eight poems, in both Irish and Latin, can be attributed to him; it is very likely (in the light of recent research) that he also redacted the body of bilingual homiletic literature preserved in the Leabhar Breac, in which case his status as a scholar must be considerably enhanced.
In his latter years he left Armagh and undertook a journey to the monastery of Lismore, Co. Waterford, where he died on the feast of St Fursa (qv), 16 January 1086. His death is noted in the annals, martyrologies, and calendars. His obit in the Annals of the Four Masters described him as ‘the senior scholar of Ireland, learned in wisdom, in piety, and in poetry in both languages’. Máel-Ísu was the first of many of the Ua Brolcháin family to merit mention in the Irish annals. His genealogy describes him as a cleric; unusually for his time, he was probably celibate, since there is no evidence that he left any offspring.