The Heckler & Koch SL9 is a semi-automatic rifle manufactured by Heckler & Koch. It is the civilian version of the Heckler & Koch G36.

The rifle fires the .223 Remington or 5.56×45mm NATO cartridge and feeds from a 10-, 20- or 30-round detachable magazine (depending on the variant of the rifle). Unlike earlier types of HK rifles, it is not a roller lock bolt but rather a lug-type rotating bolt system as seen on the AR-18.