The Triumph TR3 is a British sports car produced between 1955 and 1962 by the Standard-Triumph Motor Company of Coventry, England. A traditional roadster, the TR3 is an evolution of the company's earlier TR2 model, with greater power and improved braking. Updated variants, popularly but unofficially known as the "TR3A" and "TR3B", entered production in 1957 and 1962 respectively. The TR3 was succeeded by the Michelotti-styled, mechanically similar Triumph TR4.

The rugged ‘sidescreen’ TR, so named for its employment of removable plexiglass side curtains, was a sales and motorsport success. With approximately 74,800 TR3s sold across all variants, the model was the company's third best seller in the TR range, behind the TR7 (111,500 units) and TR6 (94,500 units) models. The Triumph was campaigned in races, hill climbs, and rallies across Europe and North America, with several outright, team, and class victories to its credit.