Mac Girr / Irish - Mheic an Ghirr - gearr originally giorr / A Sept - Family branch who had their territory in Co. Armagh - South East Ulster / They were also in Co. Tyrone - Central Ulster where some are known as Short / Mac Geer is a variant used in the north of Leinster.

Girvan / Scottish origins / They were in Co. Antrim - North East Ulster.

Mac Given or Giveen / Mag Dhuibhin or Mag Dhuibhfinn / See also Giffen / A Sept - Family branch who had their territory in Co. Donegal - North West Ulster / Mac Kevin & Mac Avin / Irish - Mheic Dhuibhin variants are also used in Co. Donegal and nearby in Co. Sligo - North West Connacht.

Mac Givern / Irish - Mag Uidhrin - odhar - dun coloured / A Sept - Family branch who had their territory in Co. Armagh & Co. Down - South East Ulster / Bickerstaff, Biggar & Montgomery are also used as synonyms for Mac Givern in Co. Down.

Mac Givney / Irish - Mheic Dhuibhne / For a derivation see Deeney / A Sept - Family branch who had their territory in the eastern part of the Diocese of Kilmore in Co. Cavan - Southern Ulster / The variants Mac Avinna, Mac Avinue & Mac Evinney where also used there.

O Glacken / Irish - Ui Glacain / A Sept - Family branch who had their territory in Co. Donegal - North West Ulster and the surrounding regions.

Mac & O Gladdery / Irish - Mheic & Ui Gleadra / A Sept - Family branch who were in the territory of the Heremonian Dal Cuinn Ui Maine in Southern Connacht / In the Mid - 17th Century they were in Co. Tyrone - Central Ulster and the surrounding region where O instead of Mac was also used.

Mac Glade / Gaelic - Mag Leid / Used as a variant for the Scottish Mac Leod.

Mac Glade / Used as an abbreviation for Mac Gladdery, which see.

Mac Glancy or Glancy / Used as a variant for Clancy, which see, in the Heremonian Dal Cuinn Ui Briun kingdom of Breifne in Co. Leitrim - Northern Connacht. *87.Brion.

Glanny or Glenny / Irish - A locative surname an Ghleanna - of the Glen.

Glanville or Glanfield / Anglo Norman origins / They have been in Ireland since the 14th Century in Southern Munster.

Glascoe / See Glasscock.

Mac Glasgow / They were in Co. Tyrone and other parts of Ulster where it was used as a variant for Mac Closkey, which see.

Mac Glashan / Usually Mheic Glasain or Glaisin - glas - green or grey green / They were in Co. Derry - North Eastern Ulster where it was also changed to Green / See Glashen & Glasier.

Glass / glas - green / They were in Co. Antrim & Co Derry - North East Ulster.

Glasscock / English toponymic origins / They were in Co. Kildare - Central Leinster / Glascoe is a synonym used for Glasscock not Glasgow.

Mac Glaughlin / Used as a variant for Mac Gloughlin, which see, in Ulster

O Glavin / Irish - Ui Glaimhin - glaimhin - glam - satirist / A Heremonian Dal Cuinn Ui Fiachrach Sept - Family branch who had their territory in Connacht / Now also found in Co. Cork & Co. Kerry - Southern Munster. *87.Fiachra.

Mac Glavin / Irish - Mag Laimhin previously Mag Fhlaithimhin - flaitheamh - ruler / A Sept - Family branch who had their territory in Ulster / Also known as Hand by translation from lamh for hand / Not connected to O Glavin / See also Glavy.

Mac Glavy or Glave / Irish - Mag Fhlaithimh - later Mag Laithimh / For a derivation see Mac Glavin / A Sept - Family branch who had their territory in Connacht and it was often changed to Hand in the belief it was derived from lamh - hand.