The Cooper T12 was a Formula Two/Formula Three racing car produced by the Cooper Car Company.

The car was developed as the long chassis version of the Cooper Mk IV design, making it eligible to use in both F3 (with JAP 0.5 L engines) and F2 (with JAP 1.0/1.1 L engines).

In 1950 it made a single outing in a Formula One World Championship race, entered by Horschell Racing Corporation for Harry Schell at the Monaco Grand Prix, where he retired. It was also used by various priveteers. Altogether it was used at 35 races, achieving two podium positions. Its only win was achieved by John Barber at the 500 Car Club Formula 2 Race.