The Heckler & Koch MP5 (from German: Maschinenpistole 5, meaning machine pistol 5) is a 9mm submachine gun of German design, developed in the 1960s by a team of engineers from the German small arms manufacturer Heckler & Koch GmbH (H&K) of Oberndorf am Neckar. There are over 100 variants of the MP5, including a semi-automatic version.
The MP5 is one of the most widely used submachine guns in the world, having been adopted by 40 nations and numerous military, law enforcement, intelligence, and security organizations. It is widely used by SWAT teams in North America.
In 1999, Heckler & Koch developed the Heckler & Koch UMP, the MP5's successor; both are available as of 2015.
Heckler & Koch, encouraged by the success of the G3 automatic rifle, developed a family of small arms consisting of four types of firearms all based on a common G3 design layout and operating principle. The first type was chambered for 7.62×51mm NATO, the second for the 7.62×39mm M43 round, the third for the intermediate 5.56×45mm NATO caliber, and the fourth type for the 9×19mm Parabellum pistol cartridge. The MP5 was created within the fourth group of firearms and was initially known as the HK54.