The AS-90, known officially as Gun Equipment 155 mm L131, is an armoured self-propelled artillery used by the British Army.

Self-propelled artillery is artillery equipped with its own propulsion system to move toward its firing position. Within the terminology are the self-propelled gun, self-propelled howitzer, self-propelled mortar, and self-propelled rocket artillery. They are high mobility vehicles, usually based on continuous tracks carrying either a large field gun, howitzer, mortar, or some form of rocket/missile launcher. They are usually used for long-range indirect bombardment support on the battlefield.