A Regular Mook is the standard opponent. Toting an assault rifle, he'll lay down fire when he detects a bro until one of them dies. He can be parachuted and can spawn from a Mook Door. Despite their low rate of fire, they are one of the more common source of deaths for anyone who does not pay attention to the "!" symbol.
Suicide Mook Edit
The Suicide Mook will search for bros, charge them and detonate. This can be a game changer in tight quarters. You're best to knock these mooks back from a distance. They will detonate shortly after they are dead. He can be parachuted and can spawn from a Mook Door.
Riot Shield Mook Edit
A Riot Shield Mook hides behind his riot shield that can withstand all primary attacks. A melee attack tosses the shield away, and his lack of other weapons makes him totally vulnerable to other attacks.
A Bruiser can take more damage. He uses a minigun, which spins up, shoots a spray of bullets, then stops for a few seconds.
A Scout Mook looks for bros and after detecting one, runs around alerting other hostile units of their presence. Any unit he passes will walk toward a bro, and suicide mooks will be lit.
Attack Dog Edit
An attack dog is a close range opponent that moves quickly and jumps onto nearby bros. Its attack kills instantly. If it finds a bro or enemy corpse, it will feed on it and become a bigger and stronger version, called Super-Size-Me Dog. This bigger dog can take more damage.
Armored Mook (AKA Robot Suit) Edit
An Armored Mook is nearly impervious to all attacks and shoots very dangerous flurries of bullets. His only weakness is a fall of three or more blocks. Bros can jump on him. After his death, bros can ride in its armor (Entered using the melee button): his fuel will deplete from jumping, and he can fly (something the mook never does). Fuel can be replenished with ammo crates. The Armored Mook can also be self-destructed using the special attack button to do moderate damage to the terrain and surrounding mooks. It will also explode when it has taken too much damage from falling and explosions. Being hit simultaneously by two Armored Mooks' fire will cause your bro to jump out and likely die. In the full release, you can eject the mook out of the suit (by pressing melee when you're standing on it) and take it over outright.
A Grenadier Mook will toss grenades in a bro's direction, and also drop one when they die. Each time one of their corpses is hit, a grenade is dropped from it. His grenades can be thrown back by pressing the melee attack near them.
Bazooka Mook Edit
A Bazooka Mook will launch destroyable rockets to bros. Their rockets are heat seeking, making them very dangerous.
Ninja Mook Edit
A Ninja Mook is an opponent who hides until a bro gets close enough. It can be hidden by a Foreground Bush Doodad.
Jetpack Mook Edit
A Jetpack Mook is an opponent who hovers above, seeing a bro. Upon death its corpse acts like a Propane Tank going to the direction he's facing before exploding.
A xenomorph with a device on its head. They are like normal Xenomorphs, except that due to the box that controls their minds, they are friendly to terrorists and hostile to bros and other aliens without brainbox. They also splash acidic blood after being killed. They are afraid of other normal aliens. They are currently not present in campaign or arcade mode(Full Release).
Alien Egg Edit
An Alien Egg spawns a Facehugger if it is touched or stepped on. Eggs can be destroyed before they hatch. They can be found on floors, walls, and ceilings.
Oval-shaped cocoons that release lethal acid drops when a Bro pass under them. If destroyed, they explode in a huge acid blast. They are also screecher eggs.
A Facehugger is a small, crawling form of the alien. It crawls on floors, ceilings, and walls, seeking a bro or mook. When the facehugger finds one, it latches onto the face and kills the bro or mook. After a few moments, an alien hatches from the host body. To prevent this, a bro must destroy the body before the alien hatches.
A stout beetle-like alien which can roll up into a fast ball and detonates when a Bro is near or runs out of time, spraying acid everywhere, there are also flying variants who crash into the ground when they see a bro.
An enormous needle similar to a backbone, these things hide in infested terrain and shoot up to impale nearby Bros.
An Xenomorph is a large, quadrupedal alien that hunts for bros and mooks. They move quickly and spawn from unseen parts of the map. When a xenomorph is killed, it splashes acidic blood. This blood does not hurt the bro, but it does dissolve parts of the ground.
Giant Xenomorph Edit
Larger Xenomorphs the size of an elephant that charge towards the player when alerted and have a much higher health count compared to regular Xenomorphs. Their corpses can never be destroyed.
Regular Mooks possessed by an evil spirit; giving them a green pallor and burning away their shirts. They revive continuously unless gibbed, decapitated, eviscerated, impaled by spikes or shot in the chest with a silenced pistol.
Mooks swollen like living bombs by an evil spirit, they self destruct in a powerful bloody explosion to kill a Bro. Spawned engorged mooks cannot move since their arm and legs are too small, but they are thrown around with demonic spells. Others are mobile and can use their legs. Upon reaching the ledge, they tend to make a small jump.
Sorcerers who wear dark hooded robes, they quickly summon Engorged Mooks and toss them like grenades.
Weak but dangerous foes, these disembodied skulls dive bomb like missiles when they spot a Bro.
Warped canine monsters with a gaping maw instead of a snout, they acquire the ability to rapidly spawn clones of themselves after eating a corpse.
Flayed Body Edit
Similar to the victims of Brodator's melee attack, these enemies pursue the Bros and latch to them at contact. They don't make any harm but hinder some movements, and can even take a hit for a Bro that would otherwise kill them. They can be thrown away by holding the melee button. The Flayed Body will hide in pools of blood inside of Hell. They are quite hard to see due to their red colouration and crouching pose, but are given away by the "?" that appears when a Bro is nearby.
Is an enormous reanimated corpse, missing its arms, eyes, and ears. It vomits a volley of acid, exploding and splitting into engorged mooks upon death.
A variant of boomer, having a paler color and a sewn mouth. Upon spotting a bro, they don't spit volleys of acid, but instead detonate themselves and release 5 lost souls.
Being the reanimated corpses of bruisers, they are quite a bit stronger than their normal counterpart. Their miniguns having been replaced by multi barreled flamethrowers, their attacks are similar to Ellen's special. Unlike their smaller kin, they do not reanimate after death.
Men and women hurt by the Mook Army, they can fight for the Bros if given a weapon (melee button).But sometimes won't follow and aren't as smart as you would think, they will run of ledges, run into mines and traps and they cannot climb walls.
Strange bald humanoids tortured by the Demons, they can help the Bros like Villagers. When killed, their mouth is left agape with their tongue dangling.
Bees are released by destroying a beehive. They attack any enemy in their reach.
Animals that will explode in a burst of bacon slices if killed with an explosive. If you current bro's melee attack is a knife, you can fly by spam-clicking melee while standing on top of its corpse.
White birds common in the sky and forests.
Dark birds found where Demons thrive.
A mutated earthworm found near alien Hives, it creates a puddle of green goo if squashed.
Revolting gray worms that swarm in Demon territory and come out the neck stumps of decapitated Undead Mooks.