Ó Fearghail is a family name of the Irish nobility from County Longford who were historically the Princes of Annaly. The patronym means "descendant of Fearghail", whose name means "man of valour". Fearghail was a great-grandson of Angaile, the 10th-century King of Fortúatha who conquered and gave his name to Annaly, and his Ó Fearghail descendants were the Princes of Annaly for 6 centuries. Angaile was chief of the Conmhaícne Angaile. The lineage of Fearghail also provided chiefs of the Dál Messin Corb and its derivative Uí Garrchon. The surname became Farrell, and it was Cardinal Kevin Farrell who was made a Prince of the Church.