The mini-boss of Reactor 4. Usually stands inside a room blocked by flesh that looks like spiderwebs; it emerges and attacks once the flesh is burned away with SHC-23. An enhanced version of a Mutant. True to its name, its defining features are extreme movement and attack speeds. However, that is its only strength. Despite being a mini-boss, it lacks special abilities and relies on raw stats, making it easy to handle with axe kiting, tasers, or flashbangs. Conversely, if you lack an axe or stun methods, you must face this 1,900 HP juggernaut relying solely on shoves. Appearance: Almost identical to a regular Mutant. A fully turned infected. The only difference is... sharper teeth? Like other Mutants, it is completely infected and blood-red. Personality: Quiet normally, but goes into a frenzy the moment it breaks free.

A special forces operative sent to kill the Reaper. Outfit: Black ballistic vest, gas mask, dual-tube night vision goggles, and a tactical helmet. A distinctive green camouflage net hangs from the helmet down to the waist. Wears knee pads and an MGF uniform. Weapon: MPV-SD equipped with a suppressor and high-capacity magazine. Carries an ammo box. Personality: Full of mischief. Constantly bickers with Pointman.

Outfit: Gas mask and a tactical helmet with a Republic of Menlo patch. Also wears a visor, a ballistic vest with shotgun shell loops, shoulder pads, knee pads, and an MGF uniform. Features: Equipped with a Halligan bar that performs similarly to an axe. Possesses execution abilities to restore health, making him useful when ammo runs out. Weapon: PMS-12T 'Hammer', Halligan bar. Personality: Extremely short-tempered. Always bickering with Operator because of the constant pranks.

Outfit: Special ops night vision goggles, a dark red tactical helmet, and a gas mask with a continuous tactical goggle lens. Ballistic vest, shoulder pads, knee pads, and MGF uniform. Features: The leader. Uses a 'Pulse Note' tablet that displays the locations of infected and allies. Weapon: SR-58 "Spearhead" equipped with a holographic sight, bayonet, and flashlight. Personality: Blunt and stoic. Constantly scolds Operator and Pointman.

Outfit: Black fire-resistant suit that covers the head, with a glass-like face shield. Wears a black mask over the mouth. Ballistic vest with patches for medical supplies and a small flashlight mounted on the shoulder. Features: Uses a red rectangular medical kit called a Medvac. Can restore his own and allies' health via injections. Weapon: VGS-45 Striker with a sight and tactical grip. Personality: Quiet.

Appearance: A horrific sight resulting from a mix of virus and radiation. In short, it has razor-sharp red claws and is bright red. The teeth are extremely sharp. It is a fully turned infected. While it maintains a humanoid shape, in reality, it is just a mass of virus and radiation that walks and runs. Its eyes glow orange. Variants include RSU soldiers or Menlo firefighters.

The weakest of the weak, even more fragile than a Lurker. Appearance: Same as a Mutant. The only difference is that there are no variants and it crawls because its legs are severed. Features: It might seem slow because it crawls, but do not let your guard down. It is surprisingly fast, and because it stays low, it is easy to get bitten if you aren't using night vision to see the floor.

Unlike other Mutants, this entity is bound to corners or racks by masses of flesh. Do not assume it is harmless because it is immobile. The moment you get close, it will grab your legs; failing the QTE results in it ripping out your heart for an instant kill. Appearance: Identical to the Reaper, but lacks a lower body and is fused to the flesh mass. Usually stays still with its eyes dimmed, but white light flares in its eyes when approached. If the QTE is successful, you can escape after stabbing the Grabby Mutant's head several times.