Not all Internet memes are about cute animals. Some are about throwing the viewer a scare, from the well-worn screamer videos (footage meant to startle by interrupting a scene with somebody screaming) to Photoshopped images with subtle sinister additions.
From this second category comes Slender Man, a spindly, tall, faceless man in a dark suit-and in some interpretations, tentacles coming from his back. First invented by a participant in an online photo contest, Slender Man has taken off in a viral example of a crowdsourced mythology, fruitful for many, owned by none.
The mysterious gentleman inspired more images and stories, which led to amateur YouTube video serial dramas and indie games. Probably the best-known is the online video series Marble Hornets, revolving around Slender Man's appearances in a student film production gone bad. The concept has gotten Hollywood's attention and is heading for the big screen in 2014.