Archibald
Archibald—This name, which is used as a Christian name in Scotland and amongst the descendants of the Scottish settlers in Ulster, is the equivalent of Gille-Easbuig, to which name it has no apparent connection, and how it came to be adopted for Gille-Easbuig (Gillespie) seems to be somewhat mystifying to those with a knowledge of the Gaelic language and literature; to them the name Archibald Gillespie appears curious, in place of Gillespie Mac Gillespie (Mac Giolla-Easbuig).
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees