If you asked the average player to describe the overall tone of Azeroth, I'd wager that a lot of them would say that it is colorful, epic, or even downright cartoonish. But in my mind, the World of Warcraft we know sometimes takes a detour from the entertaining to the downright creepy. Whether it be intentionally scary or macabre things such as giant tarantulas in Terrokkar forest or stuff that just gives you the heebie-jeebies (like the Satanic children that walk the dusty road from Stormwind to Goldshire), WoW has a lot of things that put a shiver up and down your spine.
I've seen a lot of gross, scary or weird things in game, but it wasn't until the Shattering that I had a major creepfest moment. I was flying idly over Hillsbrad surveying the damage of the area, when I noticed bears -- except they didn't look like the bears I knew from the zone prior. They were bears ... with spider egg sacs infesting their flesh. Being a major arachnophobe and having a lot of issues with parasites and the like, I took my drake out of there as fast as I could so I wouldn't feel ill.
What about Warcraft creeps you the heck out?