This is a list of stuff from posts I made in a different thread a while back.
Injector Zombie: A zombie that delivers a more potent bite. (Infection chance is higher)
Skull Cap Zombies: Zombies that have grown a second outer skull covering their head. These zombies are a little tougher to kill than normal, and make head shots less effective. Weaker bullets have a very small chance of bouncing off of them. (The skull cap trait works with any zombie, including the fearsome hulk.) Uncommon Trait
Feral Spitter Zombie: Because why the heck not? This will be a relatively rare zombie, but encountering it will make you wish you had a ranged weapon on you. Rare unit
Bone plated Zombie: A zombie that has its entire body coated in a thick bone plating. These zombies gain a slight bonus to attack, and a large bonus to defense. However there movement is slowed. Bludgeons or explosives are the best way to fight these zombies. Piercing is also pretty decent if you have a good enough skill/weapon. Cutting and plain fire won’t do very much to stop these behemoths. Bullets, arrows and throwing won’t do very much either, as most of it will just bounce off of this zombie’s body, merely leaving a scratch. (This trait works on normal zombies, brutes, and hulk zombies.) Now we can have a super durable hulk that’s really hard to kill, able to take on anything! (More so than the normal hulk) Unique trait.
Bone Horror Zombie: A somewhat fast zombie that has grown bone all over the outside of its body into large spikes. Facing this zombie in close range is not recommended as there is a chance of you cutting yourself on its spikes. (Especially if you’re using unarmed.) These guys aren’t as tough as they look though, and are actually considered easier to kill than the bone plated zombie by a lot. They’re just above a normal skull cap in terms of durability. Weaker bullets have a moderate chance of bouncing off of them. Rare unit
[T2] Digger Zombie: A feral zombie that has grown longer claws able to dig through the ground with ease. Much like the Giant Worm, this zombie will tunnel through the ground to reach you. (if possible)
[T2] Tentacle Crawler: This crawling zombie has sprouted gooey tentacles enabling it to crawl at a faster speed, as well as immobilize you with them or even disarm you.
[T2] Combustion Bloater: A bloater that has gained flammable properties to its goo. Killing it with bullets, flame, or heated weaponry will cause it to explode, and is overall not recommended. This Bloater shoots out goo at an accelerated rate causing it to catch fire and turn into a fireball of sorts which will burn the ground. (inaccurate attacks)
[T3] Combustion Bomber: Same as the Combustion Bloater, only any weapon will immediately cause this bloater to explode. Its AOE range is also bigger, and its fireball is slightly more damaging.
[T3] Reverse Mosquito (Normal Zombies only): This zombie has grown a large proboscis where it’s nose once used to be. It will attempt to inject you with a high concentration of blob/zombie virus. (whatever you want to call it). Infection chance is extremely high. This type of zombie has a hard time piercing through armor.
And some Traits
[T2] Unpredictable Stumbling - Trait: Zombie gains bonus ranks in dodging by shuffling side to side and bending in an unpredictable manner.
[T3] Vibration Dodger - Trait: Zombie gains a large bonus in dodging by swinging wildly in an incredibly fast way. In fact its swinging so fast that your eyes are having trouble keeping up with it’s body movements. This Zombie can even dodge bullets. (though less so)
[T2] Rampaging - Trait: Stuns barely even affect this zombie. It just keeps coming.
[T3] Unstoppable - Trait (Brutes and Hulks only): Stuns don’t affect this zombie, and knock-back is practically useless… Furthermore this zombie will plow through most terrain obstacles with ease, never losing speed. You better have a plan before taking these guys on.
[T2] Essence Stealer - Trait (Master Zombie only, extremely rare): This Master zombie will repair itself partially whenever it attacks (and hits) you. Additionally, upon reaching low life the Master zombie will try to escape. If it succeeds, it will try to find another zombie to eat, gaining all of it’s (useful) traits as well as repairing it’s body to full. Kill this creature on sight, for if you don’t it will just grow stronger and stronger. (If it were to find a hulk and eat it, well then…)
Also we need better hulks.
In terms of tiers Zombie -> Brute -> Hulk -> Beserker (attacks become stronger the more damage it takes) -> Titan (immune to knock-back) -> Tank (immune to stuns) -> Juggernaut (You better have a ton of explosives.)