FOXHOUND (sometimes "FOX-HOUND" or "FOX HOUND") is a group of specialist forces created by Big Boss in 1971, to replace FOX after the unit rebelled under Gene and were eliminated by Big Boss. They worked for the CIA and were designed to handle Tactical Espionage missions that regular soldiers could not handle.

They were formed in 1971 by Big Boss and Roy Campbell who were both prisoners of the incident at La Peninsula de los Muertos. The two formed the outfit in order to rise up and fight against the rebelling members of FOX, and clear the names of Big Boss, Major Zero, Para-Medic and Sigint, who were all members of FOX.

Big Boss originally commanded the unit with Campbell acting as a tactician, the two lead them in a series of intense and difficult covert operations. In 1995, Solid Snake joined the unit and aided in the rescuing of fellow FOXHOUND soldier Gray Fox from the terrorist facility Outer Heaven, and fought and presumably killed the man behind it all, who turned out to be FOXHOUND commander himself, Big Boss, who had presumably set up Outer Heaven in secret.

With Big Boss, presumed dead, Colonel Campbell was placed in command, and helped Solid Snake during the Zanzibar Land Uprising. Some time between 1999 and 2005 Campbell retired and Liquid Snake was placed in charge, and under his command, members of FOXHOUND re-instated the code name regime and chose specific specialties, and the unit flourished, until it went "rogue." Campbell was then requested to come back out of retirement and forcefully asked Solid Snake to infiltrate Shadow Moses, and kill Liquid Snake and the remaining members of FOXHOUND.

After the incident, FOXHOUND was officially disbanded with no successor unit named or known.