Some quick thoughts on horror and comics before I head out into the night....
Shock horror really doesn't work in comics. Shock horror, as I use the term, is scaring the audience by startling them; the monsters leaping unexpectedly into the frame, a sudden sound effect. This is much harder in comics, as the audience controls the pace of the experience. And people tend to take in a full page before breaking it into panels in their mind; the lead up and the payoff are noticed simultaneously, undercutting the suspense. There are structural ways to try and replicate the type of shock horror found in movies--putting the buildup on a right side page and the payoff on the next left page--but, by and large, comics that rely on shock horror don't cut it. Check out Garth Ennis' run on Hellblazer; the shocks aren't really all that shocking, even when the POV is through a man's shotgun shredded groin.
This applies to the actual images as well. For whatever reason, a dead body drawn in a comic is typically less disturbing than a dead body on film, even if the comic corpse is deployed in such a way as to try and make it horrific. In this, comics lag behind both film and prose; the images in the former are more disturbing than their comic equivalents, the image derived from the latter more potent for occurring in the mind of the reader. Though there are some comic artists that convey disturbing images--the whole of The Silent City is deeply unsettling, for example, like a painted Brothers Quay film--on the whole, the images in comics fail to shock.
What comics can do is conceptual horror. There is likely a fancy name for this found in one of Sean Collins' many papers on horror, but I'm using the term simply to refer to disturbing concepts. Read Ellis' run on Hellblazer, collected into a handy trade. The sheer human evil on display is objectively horrific; it forces the reader to imagine what human beings can do to one another without pity or remorse. For an interesting comparison of the limits of the medium, and proof of my earlier assertions, read the script to Ellis' haunted arc. Read as a script, it's creepy. Especially his description as to what was done the victim's corpse. Compare that the scene in the finished comic; and I proffer to you that the scene was scarier, more disturbing as written in the script than as drawn. And I think that John Higgins is a good artist.
There are other comics that have figured out how to generate scares in the medium. But most don't. For us horror fans out there, it's too bad they haven't.