The Cooper T45 was an open-wheel formula racing car, developed and built by the Cooper Car Company in 1958, and designed by Owen Maddock.

It competed in Formula 2 racing as well as in Formula One racing, where it won one World Championship Grand Prix, the 1958 Monaco Grand Prix, being driven by Maurice Trintignant.

The chassis remained almost unchanged, but the wheel suspension was revised.

In 1958, Frenchman Maurice Trintignant surprisingly won the Monaco Grand Prix with the Walker 2-litre T45.

Cooper finished third in the Constructor's Championship, which was held for the first time.