The English and Scottish surname Mounsey, of Norman French origin, is an habitational name from places called Monceaux, in Calvados and Orne, or Monchaux, in Nord and Seine-Maritime. These get their name from the plural form of Old French moncel meaning “hillock.” The name was brought to England by the Normans following the Norman invasion of 1066. The first bearer of the surname held the manor and estate called "Herstmoneaux" in the county of Sussex. This is recorded as "Hurst quod fuit Willelmi de Munceus" in the famous Domesday Book of 1086. Early recordings include Milisant de Munceehaus and Edoned de Munchaus in the register of the Knight Templars (Crusaders) of Lincolnshire in 1185, whilst the tax register known as the Feet of Fines for Gloucestershire mentions a William Munci in 1198. Sir Walter de Mouncy is recorded at the battle of Falkirk in 1298, and at the siege of Carlaverock, Scotland, in the year 1300.