Submachine gun
They were popularized in the 1920s and '30s as weapon of choice of American gangsters and police, in the form of the famous Thompson submachine gun, commonly referred to as the "Tommy Gun". Submachine guns rose to prominence as a frontline close-quarters combat weapon and commando firearm during World War II. They are now widely used by police SWAT, military commando, paramilitary, and counter-terror team members for a variety of situations.