Bosses are special NPCs. They are usually found at the end of Zombie Scenario, Human Scenario modes or at some certain rounds of Zombie Shelter: Coop. They are the hardest to be eliminated out of all other AI-controlled characters and also have very powerful attacks.
However, some bosses are chosen to be controlled by players in Zombie Giant mode.
- Main article: Prototype Phobos.
The first boss appeared in Last Clue. It can perform normal melee attacks, dash and stomp. When doing the stomp skill, it releases a shock wave which drops nearby players' weapons.
- Main article: Siege Type Phobos.
- Main article: Dione.
The boss appeared in Toxicity. It can swing to damage nearby enemies, do tentacle attack from the ground to send humans in the air for a while and poison spray that can do continuous damage on the victim.
- Main article: Siege Type Dione.
The boss appeared in Culvert and Decoy. It shares the same properties as the normal Dione except the red spikes and yellowish belly. Siege Type Dione evolves from Dione at Round 9 of Culvert. It cannot be harmed.
- Main article: Revenant.
The boss appeared in Decoy. Unlike the previous bosses, its attacks are flame-based which are fireballs and firestorm. It can also use Mahadash skill, similar to Phobos. When it is going to create a firestorm, the player can interrupt by activating the cooling pipes.
- Main article: Fallen Titan.
- Main article: Bio Scorpion.
The boss that appeared in Behind chapter. It is a giant scorpion modified with high technology. It can do tentacle attack, storm attack, guard and dash.
- Main article: AMP Suit.
The boss that appeared in Threat chapter. It is an infected AMP Suit. It appears in Round 1 and the players must weakens it before it destroys the main tower. At the end of the round, another AMP Suit goes to the main tower and kidnap Erika.
- Main article: Frozen Terror.
- Main article: Gluttony.
The boss that appeared in Conspiracy chapter. It has huge belly, small wings, big back legs, but small front ones. It can swallow the players into its gut and the swallowed players must get out by planting 3 C4s in the gut.
- Main article: Neid and Zavist.
The 2 female bosses that appeared in Envymask chapter. These two resembles infected giant womens. Neid is equipped with dual swords meanwhile Zavist is equipped with an armor suit.
- Main article: Laser Wing.
The boss that appeared in Omen chapter. It is an infected grasshopper. It can fly, high jump, strike the player to inflict damage, summon swarms of locust and meteor kick.
- Main article: Jack.
The boss that appeared in Memories chapter. He was an escapee from Rex Lab after the zombie virus outbreak incident but later he failed and was infected by zombies, became an evil seeking for revenge.
- Main article: Crono Athletic.
The boss that appeared in Another Truth chapter. He can perform dash attack, gun spinning and launching rocket.
- Main article: Mr. X.
The boss that appeared in Episode Choi chapter. He has a man-operating giant robot that can shoot miniguns, petrol bombs and lasers.
Mr. X Zombie
The boss that appeared in Episode Choi chapter. After the machine is destroyed, he transforms into a creature that can swim in water. It can do suction, lotus bomb attack, poison breath attack, hook and wave.
- Main article: Condemned Criminal.
The boss that appeared in Episode Victor chapter. He has a chainsaw that does high damage. Can be equipped with special iron armors.
The boss that appeared in Episode Victor chapter. He has protection with special iron armors.
- Main article: Tyrant Crab.
Tyrant Crab is able to climb walls and stay on the ceiling. It can spit poisons.
- Main article: Agent Jay.
Agent Jay is unleashed by Douglas Jacob to destroy Carlito and his Vanguard mercenaries. She is an expert assassin equipped with a pair of dagger and specialized Uzi.
- Main article: Colossus.
Colossus appears in All-Out. It is a colossal robotic that can shoot lasers, massive fire balls, missiles, and Drones.
Attack On Titan
- Main article: Armored Titan.
The boss that appeared in Attack On Titan, a sub-gameplay of Zombie Scenario. He has higher health compared to the Normal Titans and capable of performing devastating physical attacks. His screaming is able to damage anything close to him.
- Main article: RAH-66 Comanche.
- Main article: Teddy Terror.
Zombie Shelter: Coop
- Main article: Zombie Shelter: Coop.
- Main article: Zombie Giant.
In this mode, a random player will be selected as the boss and need to annihilate the humans. While human players are assisted by bots and can mount a XT-300 Goliath upon summoning to against zombies.
More than one boss can appear, depending on the number of players in the room.
- Bosses were to have their own Kill FX (as shown at the top page), but they do not show up for unknown reasons.