William V (Scottish Gaelic: Uilleam Eoin Marcas V, Manx: Illiam Juan Moirrch V; born 7 September 1950) has reigned as King of the United Kingdom, following his father's abdiction, since 1971. He is the eldest son of King Henry VII (1921-2003) and his first wife, Marchioness Cynthia of Headfort.