Also, this. Watch from the intro to the end (it's ongoing). Preferably in a dark room at night by yourself for maximum effect.

Holy shit you guys. I haven't been so thoroughly freaked out (in the good, horror movie kind of way) since...I think since I saw Mothman Prophecies, which still gives me the chills. In fact this is kind of in the same vein. Interesting how Hollywood can churn out truly pathetic slasher movies at the drop of a hat whereas a couple of guys with camcorders and YouTube access can not only attract several thousand viewers but also scare them all shitless.

Also I love ARGs. Which this soooort of counts as.

Also, for being a completely made up monster thing, Slenderman is pretty fucking scary.