Ó Fiaich was the surname of a Gaelic-Irish erenagh and Brehon family from County Fermanagh. The Ó Fiaich family were of the Cenél nEógain. It is anglicized as Fee, Fye, Fay, and Foy.
Diarmait O Fiaich, abbot of Recles Gilla Molaise Ui Gillaurain, from Tuaim, rested in Christ and was buried at Ardcarne, 1229 Tomás Ó Fiaich, 1923–1990, Archbishop of Armagh
References http://www.irishtimes.com/ancestor/surname/index.cfm?fuseaction=Go.&UserID= http://www.cregganhistory.co.uk/ofiaichcentre/arms.htm- http://www.libraryireland.com/names/of/o-fiaich.php