The ARWEN 37 is a less-lethal launcher which fires a variety of 37mm less-lethal munitions which includes direct impact batons, chemical irritant delivery munitions and smoke delivery munitions. The ARWEN 37 has 5-round rotary drum magazine.

In 1977 the British government directed their Royal Small Arms Factory (RSAF) Enfield, then part of the Royal Ordnance Factories, to develop a weapon for effective crowd control that would outperform existing weapon systems.

By 1979 a design team led by Norman Trevor Brint designed three prototypes for consideration:

After initial testing it was the Enfield XL76E1 which was chosen for further development. As almost all weapons designed or produced at the Royal Small Arms Factory incorporate the letters EN or the word Enfield into their name, and the fact that it featured a 37mm barrel, the Enfield XL76E1 was officially designated the ARWEN 37 (Anti Riot Weapon ENfield).

General production of the first generation of the ARWEN 37, the Mk I, began in 1984 in Enfield, England.

The second generation of the ARWEN 37, the Mk II, were produced in Nottingham, England.

In 2001, all ARWEN trademarks and patents were acquired by the Canadian Police Ordnance Company Inc., who began production of the third generation, or Mk III, variety of the ARWEN 37. The launcher is currently manufactured under license in Canada.

Unlike many 37mm launchers which have a smooth bore, the ARWEN 37 features a rifled barrel.