The Heckler & Koch HK416 is an assault rifle chambered for the 5.56×45mm NATO cartridge. It is designed and manufactured by the German company Heckler & Koch.

Although the design is based on the AR-15 class of firearm (specifically the Colt M4 carbine family issued to the U.S. military), it uses a proprietary short-stroke gas piston system from Heckler & Koch's earlier G36 family of rifles.

The HK416 is the standard assault rifle of the Norwegian Armed Forces and the United States Marine Corps (designated M27), and it has been selected by the French Armed Forces to replace the FAMAS and by the German Army to replace the G36 as Service rifle. Other users include the Irish Army Ranger Wing, as well as the US Navy's SEAL Team Six, who used it to kill Osama bin Laden in 2011.