Prosser is an English-language surname, derived from a Welsh-language patronym. Origin The English-language surname Prosser is considered to be a Welsh surname. The name originated as an Anglicisation of the Welsh-language ap Rhosier, or ap Rosser, both meaning son of Roger. The English-language personal name Roger is derived from the Old French personal name Roger, Rogier. This personal name is of Germanic origin, derived from the elements hrōd ("fame") and gār, gēr ("spear"). The Old French name was adopted by the Normans, and was introduced into Britain by them in the Middle Ages (replacing the Old English cognate Hrōðgār). The name became one of the most popular masculine names in the Middle Ages, and lost popularity afterwards. Until the Tudor period Welsh names generally took the format X son of Y, or X daughter of Y. The Old Welsh word for son was map, but it lenited to fap (today fab), then ap. Although some of the Welsh gentry began to adopt the English fashion for hereditary surnames even before the Act of Union between England and Wales in 1536, in general the Act marked the beginning of a gradual shift towards hereditary surnames in Wales that was not complete until the 18th century. In some cases ap was merged into the following personal name to create an hereditary name. So Ap Richard became Pritchard, ap Even became Bevan and ap Hugh emerged as Pugh. The shift from ap Rosser to Prosser is of this pattern, though the surname Rosser also occurs. The distribution of Prosser and Rosser in 1842-46 was strongly centred in south-east Wales, and largely absent from other parts of Wales. Early examples of the surname include: 1529 Richard ap Rosser was a party to two deeds relating to 'a mansion place called the Van' in Senghenydd. 1556 Morgan Lewis ap Rosser was a party to a grant of land in Llywell, Co. Brecon. Name distribution There are various sources for surname maps charting the geographic distribution of surnames. England and Wales Ancestry.com's distribution map, based on their data from the 1891 England and Wales Census, shows Prossers were strongly present in southeast Wales and the western counties of England. Particularly high concentrations were in the Welsh historic counties of Glamorgan and Monmouthshire and the English county of Herefordshire. Germany German Prossers are primarily found in southern Germany. Italy The Italian Gens Project shows there are a