February 29, 1932 - November 8, 1985
Born in Kansas City, Missouri, USA.
Known as the "Kansas City Flash", Gregory was the younger brother was Riddelle L. Gregory Jr., also a race car driver. An heir to an insurance company fortune, Gregory was well known for his youngish looks and thick eyeglasses, due to his "terrible" eyesight. He raced in Formula One between 1957 and 1965, participating in 43 World Championship races, and numerous non-Championship races. Gregory is in a distinct club of motorsport being only one of seventeen drivers to compete in all three legs of the Triple Crown of Motorsport (Indianapolis 500, 24 Hours of Le Mans and the Monaco Grand Prix) and to have won at least one of those events.
Gregory used his inheritance to buy a Mercury-powered Allard, which he drove in his first race, the 50-mile SCCA race in Caddo Mills, Texas in November 1952. He retired from that race due to head gasket failure, but installed a new Chrysler hemi-powered engine in his car to race at Sebring in 1953, where he again retired, this time due to a rear suspension failure. Gregory's first win came in just his third race, in Stillwater, Oklahoma. Changing to a Jaguar, Gregory won several races in America, including the Guardsmans Trophy in Golden Gate Park, San Francisco and a race at Offutt Air Force Base in Omaha, Nebraska. At the end of 1953, Gregory was invited to his first international sports car race - the 1000 km Buenos Aires in Argentina, which he finished in 14th due to water pump problems. Throughout 1954 and 1955, Gregory competed in European races, including the Tourist Trophy at Dundrod and the 24 Hours of Le Mans. He also won the inaugural Nassau Trophy at the Bahamas Speed Week in 1954.
Moving back to America in 1956, Gregory entered several SCCA races, often winning. In 1957, he had another attempt at the Argentine 1000 km race, this time winning. This performance got him a drive with Mimo Dei's Scuderia Centro Sud, a privateer Formula One team using the Maserati 250F. His first race was the 1957 Monaco Grand Prix, where he scored an impressive 3rd place finish, the first podium for an American in an F1 Grand Prix. He followed this with a string of good results, coming 8th in the German Grand Prix, and 4th in both the Pescara and Italian Grands Prix. Despite only competing in half of the races, Gregory ended the 1957 season in 6th place in the championship.
Gregory only competed in four Grands Prix in the 1958 season, due to injuries sustained through one of his trademark bailouts when his car was set to crash, this time in a sports car race at Silverstone in England. He did manage a 4th place at the Italian Grand Prix, and a 6th in the last race of the year, this Moroccan Grand Prix. Moving to Cooper-Climax for the 1959 season alongside Jack Brabham and Bruce McLaren, he scored two podium finishes, a 3rd place at the Dutch Grand Prix and a career-best 2nd at the Portuguese Grand Prix. However, he missed the final two races of the season, again due to injuries sustained jumping from a car moments before it crashed. He finished 8th in the Championship, and with teammate Brabham winning the World Championship, Cooper won their first Constructor's Championship. Gregory scored a pole position and set a course record at the non-Championship race at Aintree, but his contract with Cooper was not renewed for the following year.
Gregory continued in Formula One until 1965, but mainly with uncompetitive independent teams. He was unable to reproduce the results he obtained early in his career, his best being a 6th at the 1962 United States Grand Prix at Watkins Glen with the UDT Laystall team, in a Lotus 24. Running 4th, just behind eventual winner Dan Gurney at the French Grand Prix, Gregory retired with ignition problems, losing possibly his best chance at a maiden Grand Prix victory. Gregory did manage a win in the non-Championship Kannonloppet race at Karlskoga in Sweden, but this race only featured six drivers and no top teams.
After his release from Cooper, Gregory also went back to competing in sports car races, setting the overall fastest lap at the 1960 24 Hours of Le Mans. He won the 1961 1000 km Nürburgring, driving alongside Lloyd "Lucky" Casner in a Maserati Tipo 61 for the America Camoradi Racing Team. In the same year, Gregory finished 5th in the 24 Hours of Le Mans in a Porsche RS61 Spyder. 1962 saw Gregory win the Canadian Grand Prix sports car race at Mosport Park in a Lotus 19-Climax. In 1964, Gregory again competed in the 24 Hours of Le Mans, this time in a Ford GT40. He retired from the race in the 5th hour due to gearbox difficulties. The following year, Gregory teamed up with 1970 Formula One World Champion, Austrian Jochen Rindt, and the pair won the race in a North American Racing Team Ferrari 250 LM. 1965 was also the year in which Gregory raced in the Indianapolis 500, starting from the back of the grid and working his way up to 5th before being forced to retire due to an engine problem.
Gregory then began to wind down his motor racing career, continuing to compete in international sports car races with some good results including a second-place finish at the 1966 1000 km race at Monza alongside John Whitmore. Following his good friend Jo Bonnier's death at the 1972 Le Mans race, Gregory stopped racing, and retired to Amsterdam, where he worked as a diamond merchant before operating a glassware business.
On November 8, 1985, Gregory died in his sleep of a heart attack at his winter home in Porto Ercole, Italy. He had four children, Masten Jr., Debbie, Scott and Michael. Gregory was inducted into the Missouri Sports Hall of Fame in 2005, the Kansas City C.A.R.B. (Central Auto Racing Boosters) Hall of Fame in 2007 and the Watkins Glen Walk of Fame in 2012. In August 2013, Gregory was inducted into the Motorsports Hall of Fame of America.