Hunters are a species on the site that are not limited to one kind of 'build', so to speak. They can be humans, vampires, or any other person (living or undead) that wishes to make another certain species extinct. For example, a human hunter is the most common, and several of them may band together to wipe out a small group of vampires.
Another common thing with hunters is that one individual may dedicate their time to searching for a certain person of a species. A werewolf hunter may devote his time and research to finding one specific person to kill, for their own reasons, whether it be for research or something more personal.
Hunters who go after humans are most likely vampires, as vampires are 'hunters of the night'. But werewolves, hybrids, etc. also have their reasons for following after humans.
ABILITIES: Hunters only have the capabilities that their species provides them with. i.e., a vampire only has the abilities that a vampire has, a werewolf has only the ones that they were born/transformed with, etc. However, hunters may use weapons crafted by either themselves or made by someone else to aid them in their hunts. These weapons include crossbows, bows and arrows, guns, silver bullets, etc.