Gille Escoib or Gilleasbaig of Menstrie is the earliest member of the Campbell family

Clan Campbell

Clan Campbell is a Highland Scottish clan. Historically one of the largest, most powerful and most successful of the Highland clans, their lands were in Argyll and the chief of the clan became the Earl and later Duke of Argyll.-Origins:...

 to be attested in contemporary sources, appearing in royal charters dating to the 1260s. His existence is confirmed by later Campbell pedigrees

Genealogy

Genealogy is the study of families and the tracing of their lineages and history. Genealogists use oral traditions, historical records, genetic analysis, and other records to obtain information about a family and to demonstrate kinship and pedigrees of its members...

. According to these genealogies, he was the son of a man named Dubhghall ("Dugald"). However, nothing is known of this man, nor of the 4 or 5 generations of his ancestors who constitute the probable historical section these genealogies preceding Dubhghall. Gilleasbaig's first historical appearance dates to 1263, when he appeared in a charter of King Alexander III of Scotland

Alexander III of Scotland

Alexander III was King of Scots from 1249 to his death.-Life:...

, being named as "Gilascoppe Cambell". He was granted the estates of Menstrie

Menstrie

Menstrie is a village in the county of Clackmannanshire in Scotland, UK. It is about 5 miles east-north-east of Stirling...

 and Sauchie

Sauchie

Sauchie is a village in the Central Lowlands of Scotland. It lies north of the River Forth and south of the Ochil Hills, within the council area of Clackmannanshire. Sauchie is located north-east of Alloa and east-southeast of Tullibody.- History :...

 in Clackmannanshire

Clackmannanshire

Clackmannanshire, often abbreviated to Clacks is a local government council area in Scotland, and a lieutenancy area, bordering Perth and Kinross, Stirling and Fife.As Scotland's smallest historic county, it is often nicknamed 'The Wee County'....

 (but then under the supervision of the sheriff of Stirling). His next appearance, and indeed his final appearance, is in 1266, when he witnessed another royal charter at Stirling

Stirling

Stirling is a city and former ancient burgh in Scotland, and is at the heart of the wider Stirling council area. The city is clustered around a large fortress and medieval old-town beside the River Forth...

 granting favours to Lindores Abbey

Lindores Abbey

Lindores Abbey was a Tironensian abbey on the outskirts of Newburgh in Fife, Scotland. Now a much reduced and overgrown ruin, it lies on the southern banks of the River Tay, about north of the village of Lindores....

. The genealogies, and indeed later 13th century patronymic appellations, tell us that Gilleasbaig was the father of Cailean Mór

Cailean Mór

Cailean Mór Caimbeul, also known as Sir Colin Campbell , is one of the earliest attested members of Clan Campbell and an important ancestor figure of the later medieval Earls of Argyll....

, probably by marriage to the Carrick noblewoman, Afraig, a daughter of Cailean of Carrick.

The name Gilleasbaig is a modernization of "Gilla Escoib" (with a variety of related spellings, such as Gille Escoib), and is often rendered as "Archibald" in English or occasionally "Gillespie" or Giilespic.