Gormley (Irish: Ó Goirmleadhaigh) is a surname of Irish origin. The main sept of the clan originated in what was Tyrconnell, now mainly County Donegal, Republic of Ireland, in the west of Ulster, the northern province in Ireland. The Ulster branch of the clan were chiefs of the Cenél Moan and originated in what is now the barony of Raphoe in East Donegal, an area known in Gaelic times as Tír Moain. The common ancestor and progenitor of these Gormleys was Moain son of Muireadach, son of Eoghan (who gave his name to Tyrone), son of Niall of the Nine Hostages.