On the evening of May 30th, 2014, three 12-year-old girls gathered for a sleepover in the small Milwaukee suburb of Waukesha. The next morning, authorities found two of the girls, Morgan Geyser and Anissa Weier, walking along the highway. They found the third girl in the nearby woods, fighting for her life after having been stabbed 19 times with a large kitchen knife. As the retreating pair would later confess to authorities, the attack was an act of ritual sacrifice. They intended to murder their classmate in the name of "the Slender Man."
"I wanted proof that he existed," Weier told investigators. "I was afraid of what would happen if I didn't... I didn't want to find out what would happen if we didn't." She also said that she knew that if she didn’t follow through with the attack, Slender Man would "kill [her] whole family in three seconds."
Like Bigfoot, the Loch Ness monster, or the chupacabra, the Slender Man is total fiction, an internet meme blurred by curious minds into something resembling reality. It stands apart from those legendary creatures thanks to a traceable origin: While most monster lore takes hundreds of years to evolve, the being that drove two young girls to attempt murder was born in a matter of weeks, incubated in well-lit expanses of the internet.