Boyd
Boyd—MAC BUIDEACH.—Boyd is the family name of the early Earls of Kilmarnock, in Ayrshire. The name is common in N.E. Ulster. The name is found also in the Isle of Man, where, according to Moore, it was formerly written Boddagh and McBoyd. He says it may be derived from Buadach (victorious), but its correct derivation is "Son of the Buteman," as McBratney, an old Galloway name, a form of Galbraith, means "Son of the Briton" (Mac A' Bhreatnaich, the Gaelic also of Galbraith), of Strathclyde, the ancient Picto-Cymric Province of S.W. Scotland, extending to near the Ribble in Lancashire.
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees