The 3-inch gun M5 was an anti-tank gun developed in the United States during World War II. The gun combined a 3-inch (76.2 mm) barrel of the anti-aircraft gun T9 and elements of the 105 mm howitzer M2. The M5 was issued exclusively to the US Army tank destroyer battalions starting in 1943. It saw combat in the Italian Campaign and on the Western Front in Northwest Europe.

While the M5 outperformed earlier anti-tank guns in the US service, its effective employment was hindered by its heavy weight and ammunition-related issues. Losses suffered by towed TD battalions in the Battle of the Bulge and the existence of more mobile, better protected alternatives in the form of self-propelled tank destroyers led to gradual removal of the M5 from front line service in 1945.