The knife issued to special forces varies depending on the specific unit and their mission requirements. However, one of the most commonly used knives by special forces is the Fairbairn-Sykes Fighting Knife. Developed during World War II for the British SAS, it features a double-edged, thin blade that is perfect for stealthy close-quarters combat. Other popular knives issued to special forces include the Ka-Bar USMC Fighting Knife and the Gerber Mark II.