Hunters and Protectors
Hunters are those who choose to live their lives taking active part in the battle between good and evil. They can be nearly anything. Normal, run of the mill humans to supernatural creatures of almost every variety. There are a few different sorts, but it's not necessarily factions. It's more different types of mentalities common in hunters. This of course doesn't cover the full spectrum of hunters or why they hunt, they are merely examples.
The Vengeful Hunter
I'll get you, and your little dog, too! Or something like that, only a lot more intimidating. This type of hunter is the kind who probably got into this business because they were at the wrong end of something that went down that involved the supernatural. Whether it was because you and your family were in the path of a roving sadistic vampire pack, or some crazed werewolf ate your parents, you're not fucking around now. And you plan to take down who or whatever wronged you, and everything in between you and it along the way.
Kill Em All
This type of hunter doesn't really bother differentiating between good and evil supernatural beings. They are nearly universally human, but there have been a few cases of utterly insane supernaturally inclined folks that take this route. For whatever reason, they see anything supernatural as being unnatural, and therefore an affront against them and everyone else in the world. If they had a motto, it might be 'fuck you and everything you stand for'.
Bloodline
This is a pretty standard one. It runs in the family. It could go back generations, or have started in more recent ones, but it's just what your family does.
The Merc
They're in it for the money, and that's more or less it. Werewolf pelts fetch a pretty penny and demon parts on the black market is excellent money. They're not especially bothered by what they could be taking down. Good, evil, whatever. If there's a steady paycheck involved, they'll take down whatever's on the hit list.
The Martyr
These are the hunters that seem absolutely fearless. This is because they don't especially give a damn if they're brutally killed in the line of duty. They'll die for the cause (and often do).
Evil Ash (no, right now i can't think of a better name. so army of darkness it is)
You didn't think all hunters were for the side of good, did you? These hunters are the assassins for Team Evil. They specifically set out to hunt down anyone working to tip the balance in favor of the light and fluffies.
True Believer
These types of hunters are the ones who really believe in what they're doing. They're the ones who make a career out of it, dedicate their entire lives to the fight. It's because they believe they have a responsibility, they need to be helping with the fight between good and evil, etc. Like any zealouts, they're hard to take down. They're on a mission, after all. They've also been known to form their own loose groups of similarly minded people, making small networks of people to call in case of emergency or 'I cannot possibly kill this thing on my own' monsters in their path.

Protectors
Protectors are family lines of humans who's specific purpose in life is to protect someone else. It started as families designed to protect other families. Due to demonic involvement way back when, they are also cursed. Severely. In usually unpleasant, terribly inconvenient ways. Since that happened, the lines have gotten spread out a bit. There are still the protector family lines, but many of them no longer have a specific family they protect--they merely choose someone during their life to dedicate themselves to.
General Information
-Protectors are martyrs. All of them, at the core. Their entire existence is built around keeping someone else alive and well. This includes sacrificing themselves to achieve this.
-They will choose someone. They're predisposed to do it. If they don't have one, they will feel restless and incomplete until they do.
-They are not allowed to be involved romantically with their chosen to protect. Often times it is close friendships, but it doesn't have to be. Some family lines pride themselves on protecting others without them ever knowing about it. While it's happened from time to time, it's highly frowned upon and cautioned against.
-All protectors are cursed in some significant way. You may choose your family line's specific curse, and it has to remain consistent. It also has to be a major trip up. Someone really set out to screw over the whole lot of them, and they were proficient at that.
-If the protector manages to accomplish what their curse guards against, it will backlash and kill them. There is no way around this. For example, say your protector is banned from setting foot on holy ground. This doesn't necessarily mean that they can't. They're free to walk anywhere. If it happens, they will die. So say your chosen was being strangled by a maniac killer just inside a church? You could definitely run up and whack the guy with a shovel. You just wouldn't be around long enough to watch his brains dribble out the back of his skull. It's anywhere from instantaneous to about three minutes, but time is most certainly short.
-They breed like rabbits. Or, not quite in the multiples sense, but because they're really set up not to be long lived people, they are extremely prone to pregnancy/fertilization. More often than not, their first times proved to be enough. None of them are infertile, and they even have a tendency to have 'miracle' children with people who are.