Parasite Unit

Mist = Sniper = Archaea = The Parasite Unit, also known as the Skulls, were parasite-enhanced super soldiers commanded by XOF commander Skull Face. Considered to be his most fearsome assets, the Parasite Unit were given high-priority missions that the average soldier couldn't handle, given their supernatural abilities. Venom Snake first encountered them in Afghanistan and later in Central Africa.

Their prowess in combat was first hinted at when they wiped out Kazuhira Miller's unit in minutes before capturing him.

History
Sometime before the early 1980s, Skull Face discovered an old Diné man under the moniker Code Talker who had discovered a species of parasite from the remains of The End that assimilated with the vocal cords of the host and could be bred to become infectious when the host spoke a specific language. Besides being a potentially destructive weapon, certain strains of the parasite would also bestow upon the host mysterious abilities (if the body accepted the parasite). Skull Face implemented the parasites alongside additional technology to several unknown XOF operatives in order to create the "Parasite Unit", also known as the "Skulls".

Their earliest known activities include the capture of Kazuhira Miller in early 1984, whom they gave to the Soviets as a sign of good faith. Later, after Venom Snake rescued Kaz from Da Wialo Kallai, the Mist Unit of the Skulls attempted to recapture Miller along with Snake, but ultimately lost track of them and called off the search. They later reappeared during Snake's mission to acquire the Honey Bee at Da Smasei Laman, where they were ordered by Skull Face to kill him, but again failed to do so.

The Skulls were later redeployed into central Africa to personally escort a convoy armored vehicles, protecting a transport truck which carried "yellowcake" and uranium enrichment archaea. When Venom Snake managed to get near the truck, the Archaea Unit revealed themselves from the back of the truck and attempted to kill Venom Snake to prevent him from stealing the cargo but to no avail. Later during Venom Snake's mission to extract Code Talker, the Sniper Unit, a team of female Skulls, attempted to stop Venom Snake from reaching Code Talker's residence in Lufwa Valley, but ultimately could not prevent him reaching his destination. After Code Talker was extracted, Skull Face ordered the Archaea Unit to prevent Code Talker from reaching Mother Base, having them take down Venom Snake's helicopter using a cloud of corrosive metallic archaea. After succeeding in grounding the helicopter, the Skulls moved in to execute the crash survivors, but Venom Snake managed to hold them off and escape.

After Skull Face's death, the Skulls began losing control and were hunted down by Diamond Dogs to prevent them from causing mass chaos. Code Talker also assisted in the creation of the Parasite Suit for the Diamond Dogs, a special combat suit that would allow the user access to some of the supernatural abilities of the Skulls using parasites extracted from their corpses.

Personality and traits
The Parasite Unit wore technologically advanced suits that could be used as camouflage to appear as a member of a different organization. They received their powers from a species of parasite discovered by Code Talker that infested the vocal chords. It destroyed most of their cognitive functions, leaving them effectively zombies (both physically and mentally), easily fooled by stealth tactics. While Quiet was technically a Skull herself, she had a mutant strain of the parasite that left her mind intact and did not spread so long as she avoided speaking English. Members of the Parasite Unit normally came in groups of four and operated in three variations based on their capabilities and specialty.

The Mist Unit had bright, glowing cyan eyes. True to their namesake, their presence was marked by a thick cloud of cyan mist setting down on the area. When unprovoked they normally limbered around like zombies, but they were in fact extremely agile, possessing the ability to jump at heights and distances that made it appear as though they were flying for a short time. They were able to outrun D-Horse and most vehicles, leaping and bounding at incredible speeds to catch up with their targets. They had the ability to store weapons and would often use automatic firearms, machetes. They could also release clouds of metallic archaea underneath their parasite skin, releasing them at will in order to infect other soldiers and controlling them to attack on their behalf.

The Sniper Unit was an-all female variant, in which they had deep orange eyes with an augmented scope equipment covering their right eye. They acted almost identically to Quiet, possessing laser-sight sniper rifles stored inside their parasitic skins. They also possessed many of the same abilities as the Mist Unit, including their misty presence and enhanced agility and speed. However, they were somewhat frail in comparison to their male counterparts, capable of withstanding only three or four head-shots from a sniper rifle. If Snake remained hidden for too long, they would sneak up on him from behind.

The Archaea Unit behaved and attacked similarly to the Mist Unit by using automatic firearms and machetes, albeit without the characteristic mist. Their specialty lied in their ability to generate heavy amounts of archaea all over their bodies which acted as armor thus greatly enhancing their durability. They could also frequently summon/generate large chunks of explosive archaea from the ground with telekinesis as means of attacking their target. Just like the Mist Unit, they could release clouds of metallic archaea in order to infect any soldiers within their vicinity and act as their support.

Behind the scenes
The Parasite Unit are enemies that appear in Metal Gear Solid V: The Phantom Pain. They were first introduced in the E3 2013 Red Band and Green Band trailers for the game, appearing alongside the Volgin-like fiery apparition as well as the Psycho Mantis-like child under the tagline of "Those who do not Exist." They are seen in a desert jumping in the air, then landing on the ground running toward the camera. They appear to be numbered, as the centermost soldier has "02" on his forehead. E3 2015 revealed that there were also female members of this unit, one having "E2" on her forehead. They were seen confronting Big Boss and Ocelot.

Not much mention of them was made until May 2015 when gaming journalists were given a chance to play the game for a short time. These enemies were noted as being "commanded by someone familiar." Some theorized that Skull Face might have been the commander of these soldiers, making them part of XOF as possible elite members. In addition, fans wondered if Psycho Mantis was the commander of the Parasite Unit given their appearance is alongside a gas mask wearing child in the aforementioned trailer. It would later be confirmed that Skull Face is the commander of the unit.

In the Piggyback Collector's Edition Guide's Art Gallery, Hideo Kojima explained that the Skull Unit is a new arrangement of the respective models of real special forces, American comic style, mysterious individuals, beasts, and huge AI weapons for Metal Gear Solid, Metal Gear Solid 2: Sons of Liberty, Metal Gear Solid 3: Snake Eater, Metal Gear Solid 4: Guns of the Patriots, and Metal Gear Solid: Peace Walker. He also added that unlike before, they aren't merely a single boss but boss enemies that work as a team.

Gameplay
They are, as shown in the trailers, very fast and agile. They also appear to be strong, as journalists who were granted early access to preview the game have claimed they were not willing to Fulton recover them at the given time and could out-run Diamond Horse. But when they do not know the player is there, they are noted to walk in a slow, stumbling motion. The magazine articles also report that they disappear into dust in a similar manner that Quiet is seen performing, and Big Boss employs the same ability in the Metal Gear Online 3 trailer. It has also be noted that the "Skulls" wield submachine guns similar to the P90 used by Solidus Snake and the Arsenal Gear Tengus in Metal Gear Solid 2 and the FROGS in Metal Gear Solid 4. Finally, it has been revealed that during the mission to rescue Miller, the Skulls will be encountered on a bridge. This will result in a quick but exhilarating chase. They would be encountered again in Mission 6: "Where Do The Bees Sleep?", in Mission 16: "Traitors´ Caravan", and in Mission 28: "Code Talker" as boss enemies.