The Parasite Unit, also known as the "Skulls", are parasite enhanced super soldiers under the control of Skull Face in Metal Gear Solid V: The Phantom Pain.
Sometime before the early 1980s, Skull Face discovered an old Diné man under the moniker Code Talker who had discovered a species of parasite, likely a holdover from previous experiments by the Philosophers, the precursors of the Patriots, that could be bred to become infectious when the host spoke a specific language. The parasite eventually left the host in a vegetative state as the cognitive functions of the brain were destroyed. Skull Face implemented the parasites with additional technology to create the Skulls.
The Skulls have glowing green eyes. They also have the ability to jump enormous heights and distances and are quick enough to outrun a horse. they are also able to teleport .
The Parasite Unit comes in variations, some being able to create a super strong armor for themselves that can withstand most explosions and even vehicle weapons. They can also create stone-like shards to hurl at enemies, capable of dealing large damage to vehicles. Another group contains snipers like Quiet. They move quickly, use stealth, and sneak up on Snake if he remains hidden for too long. They are also the most frail, capable of only withstanding three or four headshots from any sniper rifle. A sign that shows that the Skulls are near is a mist appearing.
Their earliest known activities include the butchering of the unit of Kazuhira Miller in early 1984 and the capture of Miller himself, whom they give to the Soviets as a sign of good faith. Later after Venom Snake rescues Kaz from a Soviet controlled village, the Skulls attempt to recapture Miller along with Snake, but ultimately lose track of them and call off the search. They later reappear during Snake's mission to acquire the Honey Bee, where they are ordered by Skull Face to kill him, but again fail to do so.
After extracting Code Talker, Snake's helicopter is attacked by the Skulls, killing both pilots and bringing it down near an air base. There, Snake faces the air base personel who have now been infected by the parasite and have become Skulls as well. After defeating them, Snake is able to bring Code Talker safely to Mother Base.
- If the Skulls are extracted to Mother Base, it is possible to use their parasites to create a suit for Snake that gives him some of the Skulls' power.