Giuseppe Mastromattei (Fabriano, 17 June 1897 – Rome, 15 September 1986) was an Italian Fascist politician and civil servant, who served as prefect of Bolzano from 1933 to 1940. He was the longest serving prefect of the province of Bolzano and oversaw the forced Italianization of South Tyrol under the Fascist regime, as well as the South Tyrol Option Agreement of 1939.