As it's name implies, these Zombies are from the Resident Evil Series. They appear in many of the installments to the series and many consider them to be their signature character.
They are virus-infected creatures that move slowly toward their target. They will usually then grab their target and attempt to bite them, behavior which can be fought off in a variety of ways, sometimes with a knife, dagger, or even a stun gun or explosives, but sometimes inflict damage regardless.
They do not seem to try to kill their opponents simply for sustenance; if their target is moving too fast to grab, some versions will try to claw at their target. If their target is completely out of a normal unarmed human's strike range, the zombie will actually vomit in their direction (which is, apparently in some way, toxic.)
In some appearances, they will seem to die after taking enough damage and leave a pool of blood. After a certain amount of time, unless they are executed in a certain manner, the zombie will mutate into a faster, stronger version and come back from the dead once more. This mutation was coded the V-ACT, however, due to the very red coloration their head has taken from soaking the pool of blood it left earlier, they were nick-named Crimson heads. They seem to have grown claws, which have become their primary weapons