High-Tech Special Forces Unit FOXHOUND was an elite black ops unit of the United States Army that was established by the "Legendary Soldier" Big Boss.

Although its function changed over the years, FOXHOUND specialized in covert, solo infiltrations, to cope with local revolutions, regional complications, and global terrorist activities in "unauthorized" combat zones too politically-sensitive to intervene through conventional means. Its agents are also trained to complete various missions that are assigned in secret, to the extent that they are considered the modern versions of the ninja. All its members were battlefield hardened veterans, with many coming from a mercenary background. Because of its status as a hi-tech special forces infiltration unit, any and all members of FOXHOUND are skilled at various skydiving techniques and underwater infiltrations in order to cover all possible routes of infiltration into an enemy nation, and likewise are also knowledgable about survival over extended periods in bushes, jungles, and deserts, acute stalking, detonation operations, wireless communication, procuring and reusing enemy weapons, gathering information, varying martial arts, emergency medical operations, languages, and hi-tech devices