crawler

Crawler zombies are skinny zombies who run around on all four limbs. Based on their appearance, Crawler zombies seem to be mutated much more than regular zombies

Crawler zombies can be quite subversive and hard to see as they stay close to the floor. When killed, they will flip onto their backs, curl up, and explode, dealing damage to players in the radius, as well as emitting a cloud of green toxic gas that disorients the player and blurs their vision

When a Crawler Zombie explodes, all zombies in radius of the explosion  will die instantly, which can be helpful in clearing large groups

on the right with eletric is called Jolting crawler 

They are surrounded by a number of circles of electricity

Jolting Crawlers are skinny grey zombies that run on all fours, just like their regular counterpart. The feature that sets them apart is that they are surrounded by electricity and can shoot electric bolts from a distance. They usually sit on rooftops and shoot from above, but occasionally come down

 They are also shown to be able to jump off of walls to attack the player in a relentless and unpredictable manner

When killed, they will explode with a burst of electricity, similar to the rest of their variants. This burst does not deal damage to the player, however.

Brute Tyrant as a boss fight

Mossy licker 

The Swamp Licker is a formidable foe in any situation, and can only be killed by shooting and popping the spores on its body

when a fully grown fungal spore comes into contact with a nearby licker, causing it to mutate into a Mossy licker

as a charged shot to its chest makes it a one hit kill from any weapon. Note that Thrashers may devour zombies to recover and regain spores on their bodies.