The Irish name McGilligan is derived from the native Gaelic Mac Giollagain Sept that was located in County Derry in the North of the country. The area near Lough Foyle is known as Magilligan’s Strand and it is in the Northern Counties that the majority of descendants can still be found.
Source: IrishSurnames.com
1. Scots: Anglicized form of Gael. Mac Gille Fhaolagain ‘son of the servant of (St) Faolagan’, a personal name representing a double dim. of faol wolf (cf. Whelan and McClellan).
2. Irish: Anglicized form of Gael. Mac Giollagáin, patr. from the personal name Giollagán (a dim. of giolla servant).
Elder & McGilligan Genealogy 