DRW Zombie

Zombies are, in this case, people infected by the Wasps. Their only purpose is to find, infect, and devour humans. They were previously human beings who were infected with the parasitic larva of an unknown experimental wasp. Zombies are very resilient creatures, and can withstand tremendous amounts of injury fatal to normal humans. They exhibit some form of strength when it comes to attacking targets, but other than that they are relatively weaker then most humans.

Zombification
When bit by a zombie it usually takes around 24 hours or so to become an undead, but if a person is bit by more then one zombie multiple times then this may quicken the zombification process. This is strangely contradicted, because Frank West sustains many bites from zombies over the course of the game and never seems to become a zombie until later in the game, when his infection is revealed. However, one can assume he doesn't actually gets bitten in story canon, and it's simply a game mechanic.

Night Time
At night, zombies become more aggressive. This can easily be observed in any zombie due to their glowing red eyes during this time due to be near a Queen that has its eyes red as well.

Carrier Zombies
There are also carrier zombies that have a Queen wasp on them. These carrier zombies are often easy to spot, as they stay in one place reaching upwards as if trying to grab something (presumably the Queen on them.) Their only attack is to violently vomit blood on Frank if he gets too close. If the carriers are killed, the Queen will detach from its host. Frank may capture the Queen wasp, and kill it, in turn eradicating any zombies in the immediate vicinity.

Wii Edition
In the Wii edition, zombified parrots and poodles attack Frank as well as zombified versions of Psychopath characters.

Easter eggs
Sometimes you see a zombie that looks like survivors but only recolored and zombified

Zombies found as survivors so far.

Cheryl Jones(can be commonly noticed in a horde of zombies)

Jonathon Picardson

Ronald Shiner

Leroy

Simone Ravendark

Jolie Wu

Greg Simpson&Various Staff workers(and ones with hard hat which are unaffected by headshots)

Survivor Doom
if a survivor death scene is triggered(when a survivor's health is fully depleted) if you go to where they died you can see them as a zombie! this works for every survivor(and if you are lucky enough to encounter this glitch)Phsycopaths! you can kil the survivor zombie if they were turned into one!