An automatic grenade launcher (AGL) or grenade machine gun is a grenade launcher that is capable of fully automatic fire, and is typically loaded with either an ammunition belt or magazine.

A grenade launcher is a weapon that fires a specially designed, large-caliber projectile, often with an explosive, smoke, or gas warhead. Today, the term generally refers to a class of dedicated firearms firing unitary grenade cartridges. The most common type are man-portable, shoulder-fired weapons issued to individuals, although larger crew-served launchers are issued at higher levels of organization by military forces.