The MP 40 (Maschinenpistole 40) was a submachine gun chambered for the 9×19mm Parabellum cartridge. It was developed in Nazi Germany and used extensively by the Axis powers during the Second World War.

Designed in 1938 by Heinrich Vollmer with inspiration from its predecessor the MP 38, it was heavily used by infantrymen, paratroopers, platoon and squad leaders on the Eastern and Western Front. Its advanced and modern features made it a favourite among soldiers and popular in countries from various parts of the world after the war. It was often erroneously called "Schmeisser" by the Allies, despite Hugo Schmeisser's non-involvement in the weapon's design and production. From 1940 to 1945, an estimated 1.1 million were produced by Erma Werke.