Brett is an Irish and English surname of Breton origin. It arrived in both countries via the Norman Invasion of England and Norman Invasion of Ireland respectively. Irish Bretts who settled in County Tipperary and County Kilkenny were among the earliest Gaelicized Norman families. The given name Brett derives from the surname and can be either masculine or feminine. People with the surname. Adrian Brett (born 1945) English flutist and writer. Agnes Baldwin Brett (1876–1955), American numismatist. Bill Brett, Baron Brett (1942–2012), English politician and businessman.
https://en.wikipedia.org/wiki/Brett