My research has been ongoing for 10+ Years on the Gillespie surname, it is a complicated and interesting name. I have arrived at several conclusions.
1. The name almost certainly came from Ireland.
2. The name almost certainly came from Scotland
The Irish Gillespie
Monaig - The Journal of the Ulster Place-name Society places the Monaigh Uladh in the region of Downpatrick, which is located in the barony of Lecale (Leth Cathail). The Book of Lecan notes the Monaich Ulad of Rusat, and the Monaigh of Lough Erne. O'Curry in his Manuscript Materials mentions Monaigh Arad, being called from one of the three grandsons of Capha, in county Down.
Reeves' Antiquities of Down, Connor and Dromore places the Cenél Maelche, a sept of the Ulidians of Dal-Araidians or Dal Fiatach, near Moira (Mag Rath), county Down, or in Antrim, alias Monach. The Annals of the Four Mastersnotes Cearran, son of Colman, chief of Cenél Mailche, was slain, in alliance with the Dal-Araidhe in the year 912, at Carn-Ereann near the Ravel Water in Ulster. The Book of Ui Maine places the Cenél Mailche in Monach.
The annals make note of Mac Giolla Epscoip (e.g. Mac Gillespie) as a chief of Clann Aeilabhra, rector of Monach-an-Dúin, legislator of Cath Monaigh. O'Donovan places the Clann Ailebra in county Down (Four Masters). MacLysaght (More Irish Families) places these Mac Giolla Epscoips, chiefs of Aeilabhra in the barony of Iveagh, county Down; later becoming erenaghs of Kilraine in couny Donegal.
The Book of Lecan mentions the place-name Magh Monaigh, the four "prímthuatha na Bredcha" in Magh Monaigh in Ulster being the Cenél Dogfa, Clann Corcráin, Ui Thacain, and Artraidi. It goes on to note the Cenél Cridain in Magh Monaigh, in Ulster.
As tradition has it the the ancient Manaigh or Monaigh occupied the area near Lough Erne, giving their name to the modern county of Fermanagh. The Journal of the Ulster Place-name Societyalso noted their presence in county Down. The Monaig are often associated with the Manapioi (Menapii), a maritime Belgic tribe of Northern Gaul who are noted on Ptolemy's 2nd century map of Ireland in southeast Ireland. They spread northwards as the Fir Manach, or Monaig in Irish. Early Irish genealogists claim they migrated from south Leinster, their descent from the ancient Laiginian ancestor-god, Catháer Máir.
An early Manach genealogy (among the Uladh pedigrees): (Rawlinson)
Ragnall m. Cernaich m. Gillae Brigte m. Coscraich m. Cenndubáin m. Duiligén m. Galáin m. Cainnecháin m. Máel Tochaid m. Gilluráin m. Inglaind m. Comgaill m. Corccáin m. Manaich m. Ailella (Móir) m. Féicc m. Dáire Barraich m. Catháer Máir.
The Annals cite:
- U1056, Étrú son of Labraid, chief of the Monaig, a pillar of the glory of Ulaid, died in penitence.
- M1056, Etru, son of Labhraidh, chief of Monach, pillar of the glory of Ulidia, died, after a good life.
- U1104, Cormac ua Cormaic, chief of Monach, died.
- LC1171, Gilla-Aenghusa, son of Gilla-Espuic, viz.: the rector of Monach-an-Dúin.
- M1171, Gilla-Aenghusa, son of Mac Gillaepscoip, ruler of Monaigh at Dun (Downpatrick).
- U1171, Gilla-Oenghusa Mac Gilla-espuic, namely, by the lawgiver of Monaigh.
- M1172, Mac Giolla Epscoip, chief of Clann-Aeilabhra, legislator of Cath Monaigh, was treacherously slain by Donslevy O'Haughy, king of Ulidia. The chiefs of Ulidia, who were as guarantees between them, put Donslevy to death for it i.e. for his crime .
The Scottish Gillespie
Gillespie is both a masculine given name, and a surname in the English language. It is an Anglicised form of the Irish language Mac Giolla Easpaig and the Scottish Gaelic Mac Gille Easbuig, which are patronymic forms of a by name which means "servant of the bishop". First recorded in Ireland in the year 1175 and in Scotland a generation later in 1199, the name is believed to go as far back as 5th century Ireland. Other forms of the name include Gillaspie and Gillispie. The Gillespie families of Ireland and Scotland each have their own separate coat of arms. It is also one of the only Gaelic surnames to have its roots in Latin, Easpaig/Easbuig being borrowed from the Latin word for bishop, "Episcopus"
From my research, I have found that these families were very attached to the Kirk in Scotland and the Church lands in Ireland. Because of their relationship with the Crown, I have concluded the families mostly scattered to Canada, the American Colonies and Australia to escape religious persecution.
Because this name like many is an occupational name, it is very likely that Scottish Gillespies and Irish Gillespies are probably two seperate families.
In Scotland the name is listed many times in association with MacPherson, Clan Chattan and specifically GilliChatan Mor as the servant of the Great Saint Catain from Ireland whom probably traveled from Ireland up the "Great Glen" in Scotland to Ivernshire.