Zombies are the main enemies of the game. Killing a zombie will give you a certain amount of Cash. Their Artificial Intelligence (AI) is intelligent enough that they will constantly hunt the nearest player down until they successfully kill their target. If you aren't careful, they'll get you.
The normal zombie is the most common type of zombie found in the game.
Armored Zombies are normal zombies that wear armor, allowing them to take more damage before being defeated.
Fast Zombies are noticeably different from regular zombies, as they sprint towards the player and deal less damage.
Military Zombies are zombies that are wearing military-grade armor, which protects them from quite a bit of damage.
Crawlers are zombies that have lost their legs for whatever reason.
Crimson Zombies commonly spawn on Crimson Night, and are much more powerful than regular zombie variants. Caution is advised.
Hellhounds are extremely dangerous enemies that only spawn during Crimson Night. They are vastly more powerful and faster than any other zombie variant.
The Hellhounds used to only spawn when a PoP spawned them, but they were later added to Crimson Night, making that night much more difficult due to their immense speed and power.
Patient Zero is the main boss of the game that only spawns once during Crimson Night. He is currently the most powerful entity in the game, and extreme caution is advised, as well as a recommendation that you do not fight him alone.