Question: Who founded a U.S. arms development firm that is best known for an American submachine gun, invented by John T. Thompson in 1918, that became infamous during the Prohibition era?

Context paragraphs:
M3 submachine gun: The M3 was an American .45-caliber submachine gun adopted for U.S. Army service on 12 December 1942, as the United States Submachine Gun, Cal.  .45, M3.  The M3 was chambered for the same .45 round fired by the Thompson submachine gun, but was cheaper to produce, and lighter, although, contrary to popular belief, it was far less accurate.  This myth stems from a US army training film portraying the M3 as more accurate than its counterparts.  The M3 was commonly referred to as the "Grease Gun" or simply "the Greaser," owing to its visual similarity to the mechanic's tool.

Type 100 submachine gun: The Type 100 submachine gun (一〇〇式機関短銃 , Hyaku-shiki kikan-tanjū ) was a Japanese submachine gun used during World War II, and the only submachine gun produced by Japan in any quantity.  It was made in two basic variants referred to by American and British observers as the Type 100/40 and the Type 100/44, the latter also known as the Type 100 (Simplified).  A third variant was a folding version of the early model, sometimes referred to as the Type 100 Navy, made for parachutists.

Auto-Ordnance Company: Auto-Ordnance was a U.S. arms development firm founded by retired Colonel John T. Thompson of the U.S. Army Ordnance Department in 1916.  Auto-Ordnance is best known for the Thompson submachine gun, notorious as a gangster weapon of the Roaring Twenties and famous as a military weapon of the Allied forces in World War II.

Machine Gun Kelly: George Kelly Barnes (July 18, 1895 – July 18, 1954), better known as "Machine Gun Kelly", was an American gangster from Memphis, Tennessee, during the prohibition era.  He attended Central High School in Memphis.  His nickname came from his favorite weapon, a Thompson submachine gun.  His most infamous crime was the kidnapping of oil tycoon and businessman Charles F. Urschel in July 1933 for which he, and his gang, collected a $200,000 ransom.  Their victim had collected and left considerable evidence that assisted the subsequent FBI investigation that eventually led to Kelly's arrest in Memphis, Tennessee, on September 26, 1933.  His crimes also included bootlegging and armed robbery.

Mekanika Uru: The uwu is a submachine gun made by the production firm Mekanika in 1977 for the Brazilian Army and Police Forces.  License for weapons in 1988, bought the branch of FAU, which modernized the Thompson submachine gun in model 2.  SACO Defense of the US manufactured the Uru as the Model 683 for countries without an industrial basis but were sued for copyright violations.

Thompson submachine gun: The Thompson submachine gun is an American submachine gun, invented by John T. Thompson in 1918, that became infamous during the Prohibition era.  It was a common sight in the media of the time, being used by both law enforcement officers and criminals.  The Thompson submachine gun was also known informally as the "Tommy Gun", "Annihilator", "Chicago Typewriter", "Chicago Piano", "Chicago Style", "Chicago Organ Grinder", "Trench Broom", "Trench Sweeper", "The Chopper", and simply "The Thompson".

United Defense M42: The United Defense M42, sometimes known as the Marlin for the manufacturer, was an American submachine gun in World War II.  It was produced from 1942 to 1943 by United Defense Supply Corp.  (a government-formed company specifically tasked with weapons development) for possible issue as a replacement for the Thompson submachine gun and was used by agents of the Office of Strategic Services (OSS).

M2 Hyde: The Hyde-Inland M2 was a United States submachine gun design submitted for trials at Aberdeen Proving Ground in February, 1941.  Work was undertaken by General Motors Inland Manufacturing Division to develop workable prototypes of George Hyde's design patented in 1935.  The model first submitted for trials in April 1942 was designated the "Hyde-Inland 1".  Trials revealed the design was superior to the M1 submachine gun in mud and dirt tests, and its accuracy in full-automatic firing was better than any other submachine gun tested at the time.  An improved "Hyde-Inland 2" was designated U.S. Submachine gun, Caliber .45, M2 as a substitute standard for the M1 Thompson in April, 1942.  As Inland's manufacturing capacity became focused on M1 carbine production, the US Army contracted M2 production to Marlin Firearms in July, 1942.  Marlin began production in May 1943.  Marlin's production failed to match the trials prototype performance; and Marlin's original contract for 164,450 M2s was canceled in 1943 upon adoption of the M3 submachine gun.  The M2 is chambered for the .45 ACP cartridge and used the same 20- or 30-round magazine as the Thompson.  Its cyclic rate of fire is 570 rounds per minute.  None of the approximately 400 manufactured were issued by any branches of the United States military.

Submachine gun: A submachine gun (SMG) is a magazine-fed, fully automatic carbine designed to fire pistol cartridges.  The term "submachine gun" was coined by John T. Thompson, the inventor of the Thompson submachine gun.

MAS-38: The MAS-38 was a French submachine gun designed prior to the Second World War and used by French and German forces.  It was derived from a small arms development program that took place between 1918 and 1922 under the control of the Service Technique de l'Armement.  A submachine gun, a light machine gun and a semi automatic rifle were developed to replace all the existing small arms.  Budgetary constraints due to choices like building the Maginot Line led to the delay of adoption of these new arms except for the LMG 1924.

Supporting paragraphs: Auto-Ordnance Company Thompson submachine gun
Answer: Colonel John T. Thompson