O Gallen - Irish / Ua Gaillin. Heremonian 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: 91.Eogan the 1st King of Ailech ancestor of the Cenel nEogain, *90.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. Heremonian 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: 90.Fiachra the second Dal Cuinn King of Connacht ancestor of the Ui Fiachrach Sept, *89.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). Heremonian Dal Cuinn Ui Briuin Breifne Sept / Family branch, who had their territory in Co. Leitrim in Northern Connacht. Ancestors: 90.Brion the first Dal Cuinn King of Connacht ancestor of the Ui Briuin Sept, *90.Niall - of the Nine Hostages the 126th High King of Tara / Ireland ancestor of the Ui Niaill Septs.

O Galvin or O Galvan - Irish / Ua Gealbhain / geal (bright) ban (white). Heberian Dal gCais Sept / Family branch  descended from their Chief Gealbhan who had their territory in Co. Clare in Tuaiscert Mhumhain / Thomond / 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: Gealbhan, *91.Cas the King of Thomond. (Dal gCais).

Galwey or Galway or Gallwey / de Gallaidhe 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 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 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.