The Bren Gun was Britain's primary light machine gun of WWII. It was adopted to replace the ageing Lewis Gun by the British army in 1935 after adaptation from a Czech design.

A gas operated weapon, it fired the regular .303 inch (rimmed) rounds as used by the common Lee Enfield rifle, at a rate between 480 and 540 rpm depending on the model. A disadvantage of the weapon was that its rate of fire was much slower than its German counterparts, and it only accepted magazines, demanding more frequent reloading than belt fed machine guns. It was considered by some to have the "disadvantage" of being too accurate because its cone of fire was extremely concentrated.

Its weight also stretched the definition of "light" machine gun, often requiring it to be partially disassembled and its parts carried by two soldiers when on long marches. Despite these shortcomings, it was popular with British troops, and respected for its high reliability and combat effectivenes. It was manufactured by the Enfield armory, and is still in use in modified forms by the British military today.

The name Bren derives from Br(no) in Czechoslovakia and En(field) .