Long ago, during the time of Avatar Roku and Firelord Sozin, there lived a water bender by the name of Kendon. His full title was Kendon of the Black Water, because of the inky dark liquid he controlled. Some believed the water was black because of a poisonous chemical he dissolved within. Others assumed the color came from the blood of his victims. Still others seemed to think it was just ink that he had added, or perhaps exuded like an octopus.
He was a tall man and thin, his xylophone ribs becoming visible whenever the wind swayed his long black robes. His skin was terribly pale, bone white, leading most people to believe he was nocturnal and carried out his terrible work at night. Every time Kendon was sighted near a town or village, someone would go missing, without exception. No matter how many guards were posted, or fortifications laid, not even the Avatar could prevent the inevitable disappearance. The victim was almost always a child.
That victim would be found several days later, lying dead in a field, tree or roadside. These corpses were always drowned, their bodies waterlogged and bloated, their skin a pallid grey. Their faces would be twisted in the agony of the suffocation and the water they'd swallowed. They were never, however, found near any source of water. Kendon's trademark was the pitch black liquid that would be seeping from their orifices: the mouth, ears, nostrils and even the eye sockets, the eyes having been removed.
No one knew why Kendon did these things, or anything at all about him really, not even which tribe he had come from, or if he'd been born in the water tribes at all. All they knew was that he was akin to a force of nature; he would come, he would kill and would leave. It could not be avoided or stopped, because no matter how hard the authorities searched, Kendon could never be found.
Kendon was only rarely seen, but known and feared by all in the earth kingdom where he had chosen to reside, perhaps because of its large and widespread population. More often than not, he was just a rumor, a whisper on the lips of workers and washerwomen, a bedtime story used to dissuade children from mischief. But every so often, in a dark corner, an alley or forest edge, someone would spot Kendon, just standing there, staring back at them.
At some point, Kendon traveled to the North Pole of his kinsmen to seek out a spirit as terrible and well-known as he: Koh, the Face Stealer. No one knows how he found the spirit, or what he hoped to accomplish in doing so, but their meeting was confirmed by every person who saw Kendon afterward. Perhaps he had been hunting a child whose bending was too powerful for him, or perhaps he was afraid someone was closing in on him. Maybe he simply wanted to know why he was the way he was and did the things he did.
What is certain is that whatever Kendon wanted, he received it. Just like he had in every description of every witness who had ever claimed to see him, he remained completely still and emotionless throughout the conversation. Koh, defeated, was forced to give him the answer to whatever ancient and terrible question he had asked. And it is said that when he got his answer, Kendon grinned, grateful and satisfied. At that moment, Koh stole his face.
Now, when Koh the Face Stealer takes away a person's face, he takes every defining feature: eyes, ears, mouth, nostrils, frown lines, laugh lines, eye brows, facial hair, dimples, wrinkles and scars. What is left is a smooth, untouched, round surface the color of that person's skin. That person can no longer, see, hear, taste or smell. They do not eat, drink or even breathe... but they do not die, either. They simply exist, blind, deaf and dumb until someone kills them, or they take their own life. They are immortal, in a state worse than death. For Kendon, however, becoming faceless only made him stronger.
Whatever secret Koh had given him, allowed him to become an even more skilled hunter, abductor and killer, appearing more frequently and sometimes taking children two or three or more at a time. No bodies were found anymore, leading many to believe Koh's answer had led Kendon to some eldritch, evil, supernatural power, greater than bending itself. Sometimes, the witness described seeing his black water, snaking out from behind his back in long, menacing tendrils. This did not happen often though, because now any who saw Kendon would also, without fail, disappear. No amount of travel or protection could save them. Kendon would have his prey. This scared the populace even more, on top of the fact that Kendon looked even more horrifying without his face. It was almost as if he had wanted Koh to take it.
And for all their trying, all their redoubled efforts, no one ever caught Kendon. He lived on through the ages, adapting to the changing times, but never deviating in his ways, even as the gift of bending was slowly phased out of humanity's gene pool by the much larger, non-bender population. He still exists to this day, hunting, stalking and taking as he pleases, though his name is long forgotten.
By now you have most likely guessed who Kendon has become. He has shed his black robes for garments to match the turn of each age. He currently wears a black suit, a black or sometimes red tie and a white shirt underneath. His stark white, featureless face and writhing pitch black liquid however, have not changed at all. He can be seen occasionally in the backgrounds of photographs, and videos. Urban legends and myths sprang up around him as the internet came into being and he became the subject of many forums, discussions, speculations and chats. There have even been video games and short films dedicated to him, made for creepy fun, or perhaps just to mask the awful truth.
A new name has since been given to the unstoppable, inescapable Kendon of the Black Water. Can you guess it?
He is… The Slender Man.