Boylagh (Irish: Baollaigh) is a historic barony in County Donegal in Ireland.Patrick Weston Joyce said the name Boylagh comes from the territory of the O'Boyles. It was created along with Banagh when the former barony of Boylagh and Banagh was split in 1791 by an Act of the Parliament of Ireland.
Boylagh is bordered by the baronies of Kilmacrenan to the north east, Rapboe South to the east, and Banagh to the south; to the north and west is the Atlantic Ocean.
The barony contains the following civil parishes:
Settlements in the barony include Annagary,Burtonport,Doochary,Dungloe,Glenties,Kilrean,Lettermacaward,Portnoo, and Rinnafarset. Other features include the island of Arranmore.
The barony is thus described in the Parliamentary Gazetteer of 1846:
From "Irish placenames database". logainm.ie (in English and Irish). Department of Community, Rural and Gaeltacht Affairs.: