What makes horror?

Our protagonist flees from twisted, corrupted evil spirits that drive him from his home. He is hounded day and night by shadows on the road behind him, and uncertainty on the road ahead. Nor are his friends safe, one is attacked by a malevolent spirit possessing an old, rotten tree. Others are taken into the tombs of the damned, tormented and brought to the very brink of death. When it seems our hero may have escaped the grasp of his pursuers, they strike, and wound him in such a way that he is corrupted, damaged, and slowly, inexorably, becoming like them: a tortured soul enslaved to dark powers.

A horror story? Of course, most readers will recognize the plot summary of the first half of the Fellowship of the Ring, book one in Tolkien's Lord of the Rings trilogy. The Nazgul are some of the creepiest, spookiest, and scariest villains in literature, but despite this, they don't push LoTR cross genre into horror. Later, Tolkien's characters will be hounded through a black cavern by a demon, stumble through bogs filled with the faces of the dead, and force an undead army to serve them. And then there's the giant spiders, man-flesh eating orcs, and the soul corrupting ring, but at no point would this novel be considered horror. It doesn't feel like horror or read like horror.

Why not? I don't really know. The overt elements are there, but for some reason, I've never read a fantasy novel that crossed into the horror genre. I think it would be a very interesting read if someone wrote one, and there may be one out there I've missed, but in general, fantasy seems to kill the scary part.

I think it's the needed juxtaposition of the world we recognize with the terrible that is needed to produce horror. Lift a Nazgul up from Middle Earth and drop him in the midst of modern day New York, and I think you have a horror novel. Place the Dead Marshes in South Georgia, or the Paths of the Dead in Colorado, and you have the workings of a scary story.

I'm still thinking on it though. Maybe there's more to it than just that. I'm just not sure.