Fachtna (Fachanan) (c.554–c.600), abbot and founder of Ros Ailithir (Ross Carbery, Co. Cork), was born at Tulach Tenn, in the territory of the Corco Loígde. The Martyrology of Donegal describes him as ‘of the race of Lughaidh, son of Íth’. According to a twelfth-century note in the Martyrology of Óengus (qv) (fl. c.830) and in the Latin Life of Findbarr (qv), Fachtna was known as the son of Mongach (the hairy one), because he was born with long locks of hair.
According to tradition, Fachtna was trained by two saints, Íte (qv) and Findbarr. The later martyrologies make him an abbot of Máel-anfaid's foundation on the Blackwater, but it has been convincingly shown by Webster that these entries are a confusion with a spare entry in the earlier Martyrology of Tallaght. He later founded a monastery near the sea in the south of Ireland, and ‘there grew up a city called Ros Ailithir, in which continued always a large seminary of monks’. Ros Ailithir (wood of the pilgrim) later became a famous monastic school which survived till Norman times, probably its most famous airchinnech superior being Airbertach (qv) son of Cos Dobráin.
Fachtna is supposed to have suffered from blindness, being later cured by rubbing his eyes and face with the milk of Nessa, sister of Íte, who had given birth to a son after a long period of sterility. He was described as ‘a wise and upright man’ (sapiens et probus). He died, supposedly, at the age of 46. His feast-day is on 14 August; his name is invoked in one of the litanies in the Stowe Missal. He is patron of the diocese of Ross. The Benedictine priory of St Mary was established at Ros Ailithir in the middle of the twelfth century.