Masten Gregory (February 29, 1932 − November 8, 1985) was an American racing driver, who competed in Formula One from 1957 to 1965. Nicknamed "the Kansas City Flash", Gregory won the 24 Hours of Le Mans in 1965 with NART.
Gregory participated in 43 Formula One Grands Prix, predominantly with privateer teams; he also competed in numerous non-championship races, winning the 1962 Kanonloppet with BRP. Gregory was also successful in sportscar racing, entering 16 editions of the 24 Hours of Le Mans between 1955 and 1972, winning in 1965 alongside Jochen Rindt, driving the Ferrari 250LM.