Fathadh mac Aonghus (fl. 10th–11th centuries) was an Irish nobleman. He is the purported ancestor to the Ó Fathaigh/Fahy family of Uí Maine. The first person known bear the surname would appear to be one Cormac mac Maonach (Cormac Ó Fathaigh) who is listed as his great-grandson of the eight generation. However, if it is correct, Fathadh`s gr....