Keith Thompson

I'd like to introduce you to one of the most mind-blowing horror artists out there. This freelance artist has done work for video games, film, and recently designed the Kaiju featured in Pacific Rim. In all things he does, Thompson works with a level of detail and imagination unparalleled. The grotesque, twisted creations are all laid out in terribly logical ways, and he often explains how each came to be. He also illustrates the supernatural, creating fusions of the organic and the mechanical.
An example of his re-imagining of common creatures from folklore follows:

If you're looking for more body horror, Thompson's got you covered:

Enter, the Polyp Cavalry Steed. It just gets better once you read the accompanying description, found under Concept Art: Vehicles in his gallery. I encourage you to peruse all of his works and experience the awe-inspiring creations within.
Check out his gallery here