BSA motorcycles were made by the Birmingham Small Arms Company Limited (BSA), which was a major British industrial combine, a group of businesses manufacturing military and sporting firearms; bicycles; motorcycles; cars; buses and bodies; steel; iron castings; hand, power, and machine tools; coal cleaning and handling plants; sintered metals; and hard chrome process.

BSA Purchased Triumph in 1957 and a subsequent government-organized rescue in 1973 led to the takeover of BSA-Triumph motorcycle operations by Norton-Villiers, later known as Norton Villiers Triumph.

At its peak, BSA (including Triumph) was the largest motorcycle producer in the world.