Mac Gilsenan or Mac Gilshenan - Irish / Mheic Giolla Seanain (Descended from a son of a devotee of St. Senan) A Sept / Family branch, who had their territory in Co. Tyrone in Central Southern Ulster and now also nearby in Northern Leinster. Both Leonard and Nugent have been used as synonyms for Gilshenan with some also known as Shannon in Co. Fermanagh in the south - east of the Ulster Province.

Gilson. English origins. It was also used as a synonym for Gilsenan, which see, in Co. Offaly in the north - west of Southern Leinster. 

Mac Giltenan - Irish / Mheic Giolla tSeanain. Used as a variant for Mac Gilsenan, which see, in Co. Clare in the north - west of Thomond / Tuaiscert Mhumhain / Northern Munster were it was also anglicized as Shannon.

Giltrap. Used as a variant for the English name Gilthorpe, which see. They were in Co. Dublin and Co. Wexford in the east of Southern Leinster as a recent arrivals.

Mac Gilvarry. Gaelic / Mheic Giolla Bhearaigh (Descended from a son of a devotee of St. Barry) A variant of the Highland Scottish Mac Gillivray, which see. who were in Northern Connacht and nearby in Co. Donegal in the north - west of the Ulster Province.

Mac Gilway or Mac Gilwee. Used as variants for Mac Elwee, which see, in Co. Donegal in the north - west of the Ulster Province.

Mac Gimpsey - Irish / Mheic Dhiomasaigh. For a derivation see Dempsey. Only found around Newtownards in Co. Down in the south - east of the Ulster Province.

Mac Ging or Mac Ginn or Maginn - Irish / Mag Fhinn - fionn / fair complexion. Mac Ging used in Co. Mayo and Co. Leitrim in the Connacht Province. Mac Ginn usually used in Co. Tyrone in Central Southern Ulster. Maginn used in Co. Antrim and Co. Down in the east of the Ulster Province.

Mac Ginley - Irish / Mag Fhionnghaile - fionnghaile / fair valour. A Sept / Family branch, who had their territory in Co. Donegal in the north - west of the Ulster Province. Not connected to Mac Kinley.

Mac Ginly - Irish / Mheic Fhionn Ladigh -

O Ginnane - Irish / Ua Cuinneanain - Conn / Ua Cuineain / Conan. Later Ua Gaibhneain. A Sept / Family branch, who had their territory in the west of Co. Clare in the north - west of Thomond / Tuaiscert Mhumhain / Northern Munster and are also in the north of Co. Tipperary in the north - east of Ormond / Aur Mhumhain / North Eastern Munster. They are now known as Mac Guinane in Co. Offaly in the north - west of Southern Leinster.

Mac Ginnelly. Used as a variant for Mac Ginley, which see, in Co. Mayo in the mid - west of the Connacht Province.

Mac Ginnell - Irish / Mag Fhionnghaile. A Sept / Family branch of the Mac Ginleys, which see, who had their territory in Co. Donegal in the north - west of the Ulster Province and later settled in Co. Westmeath in the south - west of Northern Leinster.

Mac Ginty or Mac Ginity or Maginnity - Irish / Mag Fhinneachta. Also a derivation as Finaghty. A Sept / Family branch, who had their territory in Co. Donegal in the north - west of the Ulster Province. Mac Ginty and Mac Genty now used in Northern Connacht. Not connected to Mac Entee although Mac Ginty and Mac Genty were used in Co. Monaghan in Southern Ulster as synonyms for Mac Entee. See also Gaynor.

Mac Giollamocholmoge. A Sept / Family branch, who had their territory in Co. Dublin in the north - east of Southern Leinster where they were Kings.

Mac Girl or Mac Gerl or Mac Garrell - Irish / Mag Fhearghail. (For a derivation see O Farrell / Ua Fearghail.) Also anglicized as Mac Garrell and Mac Gorl. Now mainly found in Co. Leitrim in Northern Connacht and nearby in Co. Cavan in Southern Ulster. If Mac is used instead of Mag as in Co. Donegal in the north - west of the Ulster Province the name is Mac Carrigle / Mac Cargill / Mac Carkill.

Mac Gorl. A Sept / Family branch, who had their territory in Co. Leitrim in Northern Connacht and Co. Cavan in Southern Ulster. When Mac not Mag is used / Mheic Fheargail as in Co. Donegal in the north - west of the Ulster Province it becomes Mac Carrigle / Mac Cargill / Mac Carkill.