The story of 'Slender Man' -- the internet's creepiest urban legend

HBO's new documentary about Slender Man — a tall, shadowy monster that has terrified people on the internet for years — will finally premiere on January 23, 2017 . The character may be fake, but he has also inspired some tragic real-life attacks. Here's a look at the origins of Slender Man and how he has captured the imagination of people online. Follow Tech Insider: On Facebook