If there's one thing I've learned while writing horror--there's not one definition of this genre. So many lines are crossed, many sub-genres created only to try making sense of what horror really is.
Some of these are my favorite! Vampire and werewolves make great protagonists. Some great books showcasing vampires are: Holly Black's THE COLDEST GIRL IN COLDTOWN, Heather Brewer's VLAD TODD series, or Anne Rice's INTERVIEW WITH A VAMPIRE. As for werewolves, there are so many different stories like: Maggie Stiefater's SHIVER series or Andrea Cremer's NIGHTSHADE series.
Ghosts and demons can be great fodder for readers, too. ANNA DRESSED IN BLOOD by Kendare Blake is a fantastic example of a pure ghost story.
These horror stories are the goriest. Ever hear of Texas Chainsaw Massacre? Yeah, that.
Honestly, I don't know of any books like this for YA. Most of the blood and guts is saved for the adults--predominately in film.
The Walking Dead brought zombies back into the mainstream on TV, while authors like Jonathan Maberry and Courtney Summers write about them for YA readers. Pretty much the setting is post apocalypse, with few survivors and a lot of dead shuffling around.
There has been a little conversation on Twitter lately on how these zombies, with no brain function, have super human strength--food for thought,
This type of horror is often interchangeable with the dark contemporary genre. What's the difference? Many may contend that dark contemporary is more psychological and the latter is more violent, ie. serial killers and may have some paranormal aspects.
Mostly, mental conflict drives this type of story. The characters are real, and what happens in their mind drives something crazy. Often times the main character doesn't even acknowledge what they're doing is considered to be wrong. Think LIVING DEAD GIRL by Elizabeth Scott.
This type of horror combines horror and romance--what's not to love about this? Combined with dark settings and atmosphere, we get a very distinct story. Kami Garcia and Margaret Stohl do this best with their BEAUTIFUL CREATURES series.
This is just the tip of the iceberg. There is so much new horror being written that also crosses genre--especially science fiction. Authors are so good at creating new stories that I'm sure this list will become obsolete in a short amount of time. For now, enjoy reading and writing. Don't worry about what neat little box to fit your story into.