- "It comes out of the Earth, like Satan himself."
- ―Jean Rose[src]
The creature, which has no formal name, is shown to have a large head and four retractable claws on the end of long tentacles, one on each corner of its face. It is described in the Journal entry image as a unique mutation with an incredibly tough, carbonized exoskeleton that is somehow made from compressed coal. In combat, Satan usually reveals its head and hardly reveals its body, and the only known weakness in its otherwise powerful body is in its eyes. It also secretes saliva that has the effect of mutating Grims in the same as the Mutator would do. It is highly likely it would have the same effect on a human.
Satan's precise origin is unknown; it is said to have suddenly come up from the mines below Mount Pleasant and devastated the town. Efforts to kill it proved futile; Jean claimed it had killed more than a hundred people in the few months since it had first emerged. According to Jonathan Rose, a recent hunting party of twelve was sent to hunt down Satan that was slaughtered down to one survivor, who lost one arm and half a leg. Joseph Capelli, John Harper, and Jonathan Rose hunted down the creature, though Satan badly wounded the priest, and he was left behind. Ultimately the creature was killed by Capelli and Harper as it tried to corner them in a service elevator.
- This Chimera serves as a boss in the mines of Mount Pleasant. Its body is invincible, and cannot be hurt by gunfire of any kind. However, this is not much of a problem, seeing as how Satan rarely ever shows its body.
- Much of this fight is scripted. The first part involves running through the tunnels away from Satan, as it attempts to kill Harper and Capelli. Simply follow Jonathan during this part to stay alive. However, if you start to fall behind, you will be killed.
- Eventually, Satan will smash its head through a wall, and attempt to kill John and Capelli. During this part, the player must shoot the massive Chimeras' eyes to temporarily blind it. The Bullseye is recommended to attack the eyes due to its high accuracy and rate of fire.
- When Satan is blinded, the player must then throw an acetylene tank into its mouth and then shoot the tank to detonate it and cause major damage to the beast. Satan will then back off, and John will beg you to go after it and kill it, as he cannot due to the fact that he was injured in the battle.
- The player must then run through a series of tunnels again, while being chased by Satan. Make sure to retreat into the smaller tunnels as much as possible, as you will not be able to outrun it. Just keep retreating into the tunnels while moving forward, and you should be able to stay alive.
- While fleeing the beast, you will board a powered minecart and make an escape; Satan will pursue you, and while you cannot kill it with your conventional weapons, the more "damage" you inflict on it, the more it will slow down, and you must keep shooting to make sure it doesn't catch up to the minecart. A high-powered weapon such as the Wildfire is suggested here.
- The final part of the boss battle is very similar to before, except this time Satan will actually burst through the wall into the room with Capelli. You have to retreat into a small recess in the side of the room to survive.
- Satan will then attempt to eat you, but won't be able to reach you in the recess. Simply shoot its eyes again to blind it, then throw an acetylene tank into its mouth. Shoot the canister to detonate it, and Satan will finally die, by having its head blown completely into pulp.
|“|| This feral monster is the product of years of incubation in the coal mine of Western
Pennsylvania. It is a biological and evolutionary mystery.
- Doctor Malikov's journal entry on Satan states that the exoskeleton may be harder than diamond, adding "is this possible?" This seems to imply the exoskeleton is made from carbon nanotubes, a form of carbon which is indeed harder than diamond and which Malikov would be unlikely to be familiar with.
- In the church, one of Satan's tentacles will burst through the floor and drag a Grim underground, implying that without humans to feed on, the giant creature has turned to eating other feral Chimera.
- Satan appears as a background character in Sony's PlayStation All-Stars Battle Royale. Satan appears in the Time Station stage.