The Illuminati are a shadowy, front organisation hidden deep within the bowls of Area 51, a top secret American Military Complex. The Gray Aliens, Dr Cray Faction and Mr White Illuminati Organisation created a Treaty. The Illuminati signed an aggreement with Dr. Winston Cray and the Grey Aliens which allowed them to work effectively for a period of time. They have some control over the american goverment since they did their various projects without the goverment knowing it. While there actions are evil, from their point of view they're doing the best for humanity.
The Illuminati are encountered right after the player gains their mutagen powers, as they can be seen right after the player leaves the leaper infested room.
The Illuminati usually fight in squads, and will try their best to take the player out. They use all of the same weapons that the player can use including the shotgun, Viper assault rifle, BBG-11, and Sniper Rifle. The only weapons that the Illuminati do not use are the Scorpion pistol and the MC-11 Meson Cannon. Most of the time they are seen using the Viper assault rifle and the BBG-11 and are rarely seen using the shotgun or sniper rifle, although it could possibly be due to the fact that they are proficient with the Viper assault rifle and BBG-11.