The Cooper T43 was a Formula One and Formula Two racing car designed and built by Cooper Car Company for the 1957 Formula One season, first appearing at the 1957 Monaco Grand Prix in a works car for Jack Brabham. The T43 earned a significant place in motor racing history when Stirling Moss drove a Rob Walker Racing Team T43 to win the 1958 Argentine Grand Prix, the first World Drivers' Championship win for a mid-engined car. Despite this achievement, the car was superseded almost immediately by the T45. The T43's last appearance in a World Championship event was the 1960 Italian Grand Prix.