The SU-122 was a Soviet self-propelled howitzer or assault gun used during World War II. The number "122" in the designation represents the caliber of the main armament, a 122 mm M-30S howitzer. The chassis was that of the T-34.

An assault gun is a type of self-propelled artillery which uses an infantry support gun mounted on a motorized chassis, normally an armored fighting vehicle, which are designed to provide direct fire support for infantry attacks, especially against other infantry or fortified positions. Assault guns were pioneered by the Soviet Union and Nazi Germany during the 1930s, initially being self-propelled guns with direct fire in mind, with Germany introducing the first purpose-built assault gun, the Sturmgeschütz III, in 1940.