Kittelsen did a lot of paintings and drawing for fairy tales, but much of his work has a "weird fantasy" vibe that is perfectly creepy and more than just a bit unnverving. Check out some of my favorites of his:
|The Water Spirit|
|Creeping, Crawling, Rustling, Bustling|
|Pesta on the Stairs|
|The Sea Troll|
Much of his art looks like it would fit in perfectly in James Raggi's game, and I mean that as a high compliment. Best of all, Kittelsen's is public domain, so you don't have to have any qualms about using it. His art seems pitch-perfect for a lot of eerie fantasy.