The Irish surname Gallagher is an anglicized form of Gaelic Ó Gallchobhair ‘descendant of Gallchobhar’, a personal name from the elements gall meaning “strange or foreign” and cabhair meaning “help or support.” The name Gallagher is the fourteenth most numerous in Ireland, and is chiefly found today in the provinces of Ulster and North Connacht. The Ó Gallchobhair sept claims to be the most senior family of the Cenél Conaill. The sept's territory was spread across the areas within the modern baronies of Raphoe and Tirhugh in Co Donegal. From the 14th century until the 16th century, the sept's chiefs were marshals in the O'Donnells' military forces.