Gillespie (/ɡɪˈlɛspi/) is both a masculine given name, and a surname in the English language. The given name is an Anglicised form of the Gaelic Gille Easbaig (also rendered Gilleasbaig), meaning “bishop’s servant”.[1] The surname Gillespie is an Anglicised form of the Scottish Gaelic Mac Gille Easbuig, and the Irish Mac Giolla Easpaig, both of which mean “servant of the bishop”.[2] The given name itself is derived from a word of Latin origin.[3] Specifically, the Old Irish epscop being derived from the Latin episcopus.[4] An early example of the name in Scotland occurs in a charter dated 1175–1199, recording a certain “Ewano filio Gillaspeck”.[3][5] In Ireland, a family bearing the surname occupied the office of toísech of Clann Aílebra in the late twelfth century.[6] In 1172, for example, the toísech was slain by Donn Slébe Ua hEochada, King of Ulster. This slain Mac Gilla Espuic may be identical to a certain Gilla Óengusa mac Gilla Espuic, rechtaire of the Monaig of Ulster, who is earlier recorded in the king’s service.[7] Whatever the case, a later family bearing the surname appears on record as erenaghs of Kilraine in County Donegal. During the sixteenth- and seventeenth-centuries in Ireland, the surname is most common in Ulster.[6] During the nineteenth century in Ireland, the surname was most numerous in the counties of Antrim, Donegal, Armagh, and Tyrone.[8] Scottish Gaelic forms of the surname include GillEasbuig,[9] and GillEasbaig.[10]