Private military company

Private Military Companies or PMCs are "Mercenaries-For-Hire", consisting of soldiers employed to take part in military action and often belonging to a state which is not directly involved in the conflict. Usually hired warriors, wanting pay for their duties, mercenaries are often known by the government but rejected. Although rejected, if the time comes when a nation needs extra troops or "dirty work" to be done, they would probably hire these mercenaries. Most mercenary groups often break off of former government or military, like with Gurlukovich's group of Pro-Communist soldiers. During the peak of the war economy, an individual PMC could be powerful enough to effectively run a country, as seen in the South America when the story of Solid Sun takes place.

In tune with the war economy, numerous smaller and local scaled PMCs are also prevalent, such as in the Middle East, where private operators are hired as battlefield commanders and trainers for the militia. According to Otacon, most of the militiamen Snake encountered in the Middle East actually belonged to a nameless PMC, where most of the local men turned to for employment out of desperation. According to Campbell, the rebel army in South America has also managed to hire their own PMC for assistance, although they are never found in game.

In 2014, the five largest group of PMCs were all are working under a single mother-company named Outer Heaven, which is in turn ultimately headed by Liquid Ocelot. Logistically, technologically, and tactically advantaged, they are deployed all over the globe with the use of high-tech, high-end technology on the battlefield, and can come in and out of any conflict with minimal casualties.