Maguire (also spelled MacGuire or McGuire) is an Irish surname from the Gaelic Mag Uidhir, which is “son of Odhar” or “son of the dun or dark coloured one”. According to legend, the eleventh in descent from Colla da Chrich, great-grandson of Cormac mac Airt, monarch of Ireland about the middle of the third century. From the 13th to the 17th centuries, the Maguires were kings of Fermanagh. Using the spelling of Maguire is much less common than McGuire.

The Maguire sept is primarily associated with modern-day County Fermanagh. They possessed the entire county, also known as Maguire’s Country, from about 1250 C.E. and maintained their independence as Lords of Fermanagh down to the reign of King James VI & I, when their country was confiscated like other parts of Ulster. The Maguires supplied Chiefs or Princes to Fermanagh, from about A.D. 1264, when they supplanted the former Chieftains (O’Daimhin, or Devin). They were inaugurated as Princes of Fermanagh on the summit of Cuilcagh, a magnificent mountain near Swanlinbar, on the borders of Cavan and Fermanagh; and sometimes also at a place called Sciath Gabhra or Lisnasciath, now Lisnaskea.

The family was first mentioned in the Annals as early as 956 AD and have always been closely associated with the other leading septs of Ulster such as the O’Neill and the O’Donnell. They spawned several well-known branches which became septs in their own right, including Mac Manus, Mac Caffrey, Mac Hugh, and several others. The name is among the forty most common names in Ireland, among the top twenty-five in Ulster, ten in Co. Cavan, thirty in Co. Monaghan and is the single most common name in Co. Fermanagh. Maguiresbridge in Co. Fermanagh (Droichead Mhig Uidhir) takes its name from the family.

There are two different Maguire / McGuire YDNA Septs – named Airghialla1 (DF21) (a subgroup descended from the Three Collas) and Airghialla2 (L513).

Airghialla1 McGuire’s are L21 > DF13 > DF21 > Z3017 > Z16267 > Z3003 > Z3006

Airghialla2 McGuire’s are L21 > DF13 > L513 > S5668 > Z16340 > FGC9807 > FGC9795