It’s not often you can pin point the moment when a folklore event begins, but thanks to the Internet there is one example where we can definitely say a folklore event took hold of the public imagination.
The Slender Man is a fictional supernatural character that originated as an Internet meme created by Something Awful forum user Eric Knudsen (a.k.a. "Victor Surge") in 2009. The Slender Man is shown as a thin, unnaturally tall man with a featureless face, wearing a black suit. The character has the unfortunate habit of following people around until they become insane or disappear. The Slender Man took off and has since become a widespread figure in popular culture, appearing in fiction and art. People even began to claim real-life encounters with what is known to be a fictional creation (although to be fair there is a German myth of something similar to the Slender Man that predates the internet).
Sadly, the interest in this strange and unnerving creature ended in tragedy when two 12-year-old schoolgirls from Wisconsin tried to murder their classmate in order to win the character’s favour. The Slender Man may be a fictitious figure but he certainly seems to resonate with something deep in the human psyche.