Grier, Greir, Greer
Grier, Greir, Greer, Grierson, Gregson, Greg, Gregg, and Gregory, Gregorson, Gregor—These names are the anglicised forms of McGregor; some being the name of M'Grier. The clan Gregor, like the Galbraiths, and McLamonds, were outlawed in the early part of the 17th century, and an order of dispersal of the clan by "fire and sword" was issued against them by James VI. They were forbidden to use their own names, hence the various anglicised forms that appeared at an early period. Previous, in the 14th century, branches of the clan settled in Dumfries County, under Gilbrid Mac Gregor, son of Maol-Colum Mac Gregor, who died in 1374, where they, in later centuries assumed the names of Grierson, Grier, and Gregson, families of the Griers of Lag, Dumfries Co., settling in Co. Tyrone, and at Lurgan, Co. Armagh, and under the name of Gregson extending into the North-Western counties of England, in Cumberland, Westmoreland, and Lancashire.
The names in Gaelic are written Mac Greagair.