Colonel Abiel Bethel Revelli di Beaumont, also known as Bethel Revelli, was an Italian engineer and military officer.
Born into a regal family of ancient Piedmontese heritage, he enlisted in the Italian Army as an officer early in his adulthood. In 1911, he designed a machine gun which was produced by FIAT and adopted by the Army in 1914, serving as their standard machine gun throughout World War I. In 1914 he designed a pistol-calibre, twin-barreled machine gun, commonly known as the Villar Perosa after its manufacturer, Officine di Villar Perosa. The Villar Perosa gun is considered the first submachine gun in history, and saw use by the Italians from 1915 to 1918. In response to criticism made towards the Villar Perosa's ergonomics, Revelli developed a single-barreled carbine variant of the gun in 1919, which was bought by the Italian Army and used during the Abyssinian War in 1935 and later during World War II.
Revelli also designed some experimental weapons that were never fully developed, including an automatic rifle and a four-barreled pistol. After he died, one of his sons, Gino, founded the Società Autonoma Revelli Manifattura Armaguerra for the manufacture of the Armaguerra Mod. 39. Another of his sons, Mario, went on to become a famous automotive designer and racer.
- Glisenti pistol (1906) - Pistol
- Genovori-Revelli Mod.1909 (1909) - Self-loading rifle
- FIAT-Revelli Mod.1914 (1911) - Machine gun
- Revelli Mod.1912 (1912) - Self-loading rifle
- FIAT Mod.1915 "Villar Perosa" (1914) - Twin-barreled submachine gun
- FIAT-Revelli (1916) - Submachine gun
- SIA Mod. 1918 (1918) - Light machine gun
- Revelli O.V.P. (1921) - Submachine gun