O Gallen - Irish / Ua Gaillin. A Heremonian Ui Cobhthaigh Dal Cuinn  "Northern" Ui Niaill Cenel nEogain Sept / Family branch, who had their territory in Co. Donegal in the north - west of the Ulster Province. Also used as a variant for Gallon, which see. Ancestors - *88.Eogan the 1st King of Aileach (Cenel nEogain), *87.Niall of the Nine Hostages the 126th High King of Tara / Ireland (Ui Niaill).

Mac Gallery. Originally anglicized as Mac Gilleragh - Irish /  Mheic Giolla Riabhaigh - riabhach / brindled. A Sept / Family branch, who had their territory in the Barony of Clonderlaw in Co. Clare in Thomond / Tuaiscert Mhumhain / Northern Munster. See also Mac Areavy, Mac Gilrea, Mac Kilrea and Mac Kilroy.

O Galligan - Irish / Ua Geallagain. A Heremonian Ui Cobhthaigh Dal Cuinn "Northern" Ui Fiachrach Sept / Family branch,  who had their territory in Co. Sligo in the north - west of the Connacht Province who are now often known also as O Gilligan, which see. Many are also still known as O Galligan in nearby Co. Cavan in Southern Ulster where their name was also anglicized as White, which see - geal / white. Ancestors - *87.Fiachra the original 2nd King of Connacht (Ui Fiachrach), *86.Eochy "Mugmedon" the 124th King of Tara / Ireland.

O Gallinagh or O Gallina - Irish / Ua Gailinigh - gailineach / flattering. A Sept / Family branch, who had their territory in Co. Donegal in the north - west of the Ulster Province.

O Gallivan. A Sept / Family branch, who had their territory in Co. Kerry in Iar Mhumhain / South Western Munster. See also O Galvin.

Mac Gallogly - Irish / Mheic an Ghalloglaigh - galloglach / galloglass. A Sept / Family branch, who had their territory in Co. Donegal in the north - west of the Ulster Province. Now changed to English and Englishby in Co. Antrim in the north - east of Ulster, and some to Ingoldsby. Gologly also used in Co. Monaghan in Southern Ulster.

O Gallon - Irish / Ua Gallain - gallan / stone. A Heremonian Ui Cobhthaigh Dal Cuinn Ui Briuin Breifne Sept / Family branch, who had their territory in Co. Leitrim in Northern Connacht. Ancestors - *87.Brion the original 1st King of Connacht (Ui Briuin), *87.Niall of the Nine Hostages the 126th High King of Tara / Ireland (Ui Niaill).

O Galvin or O Galvan - Irish / Ua Gealbhain - geal / bright - ban / white. A Heberian Dal gCais Sept / Family branch  descended from their Chief Gealbhain who had their territory in Co. Clare in Thomond / Tuaiscert Mhumhain / Northern Munster who then spread out into the surrounding Counties, especially into Co. Kerry in Iar Mhumhain / South Western Munster where they are known there as O Gallivan. Ancestors - *91.Cas (Dal gCais) the King of Thomond.

Galwey or Galway or Gallwey / de Gallaidhe. They came into Ireland around the 13th Century AD and were mainly in the Ulster Province, but some were also in Co. Cork in Southern Munster where Galweys were a leading family. Although their name in Ulster was derived from Galloway in Scotland, others may also have derived their name from Galway itself.

Gamble - gamal / old. Swedish origins. They were in the Ulster Province and Co. Cork in Southern Munster in the 17th Century AD and are now more prominent in Ulster.

Mac Gammon. With Mac - a rare name in the west of Co. Clare in the north - west of the Munster Province. No Irish name found as yet.

Mac Gammon - gambon / leg. French origins. They were in Co. Waterford in the south - east of the Munster Province.

Mac Ganly or Mac Gantley - Irish / Mheic Sheanlaoich - sean / old - laoch / hero or warrior. A Sept / Family branch, who had their territory in Co. Leitrim in Northern Connacht. Also used as a variant for Shanly, which see.

Mac Gann - Irish / Mag Annaidh. Used in the Connacht Province as a variant for Mac Cann, which see.