Fer-dá-Chrích (d. 748), also known as Áed grandson of Aithmet, was abbot of Dairinis and a prominent member of the Céli Dé reform movement in the eighth-century Irish church. The familiar name ‘Fer-dá-Chrích’ (man of two districts) was accorded to several distinguished ecclesiastics, including the sixth-century Mac-Caírthinn (qv) of Clogher and Feradach (d. 768) son of Suibne, abbot of Armagh. Áed grandson of Aithmet, however, probably belonged to the lineage of Uí Aithmit Chaiss which claimed descent from Deilgíne son of Garrchú, an early dynast of Dál Messin Corb. According to a note in the Martyrology of Óengus he was a maternal uncle of Máel-ruain (qv) of Tallaght, which would make him a brother of the latter's mother, Broicsech.
Fer-dá-Chrích seems to have commenced his career at Daire Eidnech (Co. Tipperary), the site later known as Daire na Flann, now renowned for the Derrynaflan chalice. In the first half of the eighth century, the Céli Dé reform movement was being promoted in Munster, and Fer-dá-Chrích became one of its early advocates. His attention to both the spiritual and intellectual dimensions of the religious life influenced Máel-ruain and his student Óengus (qv) (fl. c.830), author of the Martyrology of Óengus (‘Félire Óengusso’) and possibly also the Martyrology of Tallaght. Fer-dá-Chrích became abbot of Dairinis on the Blackwater (west Co. Waterford), the location at which the ‘Collectio canonum Hibernensis’ had been in part compiled. He died in 748, and is commemorated in the martyrologies at 15 August and 6 October. One of his successors at Dairinis was a kinsman, Daniel grandson of Aithmit (d. 778). His church bell was brought to Tallaght, where it was venerated as a relic.