He has a pale, faceless head. He is freakishly tall, and thin as a switchblade.

Clad in a dark suit, he silently radiates malevolence and doom. Some say he lives in the deep woods, but can teleport himself anywhere to grab you with his long tentacle arms.

He is the Slender Man, a mythical predator and Internet sensation whose greatest skill is the ability to strike terror in the hearts of teens who aren't frightened by much else.

"He's one of the scariest things out there," said Dan Hughes, a senior at Mahtomedi High School. "Sometimes when I'm in the basement, I tell myself, don't think about Slender Man! And of course the more I try not to, the more I do."

Every generation has its iconic boogeymen, and this one has plenty.

Popular culture couldn't be more saturated with vampire and zombie books, horror movies and paranormal reality shows, but young people are finding that the Slender Man strikes a deeper, more shivery chord. Because he's so mysterious, all the threat and danger are created in the eye of the beholder.

Hughes said that violent shock fests like "Saw" and "Hostel" have nothing on the Slender Man.

"Those kinds of things are more about gore, which I don't find scary," Hughes said. "The Slender Man imagery uses psychology to make you scare yourself if you think too much about it."

Slender Man is also more frightening to Hughes' generation than iconic Hollywood creations like Freddy Krueger of "Nightmare on Elm Street" and Michael Myers of "Halloween," he said:

"Slender Man would make a great horror movie, but I like that you don't see him in movies or TV, that it's more like urban-legend folklore. That makes it scarier, because it seems like it could maybe be real."

James Van Fleet, who reflected on the phenomenon on his blog Horror Films 101, wrote that Slender Man has a potency that goes beyond definition. "Certainly there's the distance, and the stillness, and that monochrome anonymity," he said. "But mostly, there's that nagging voice inside that whispers this should not be here."

Despite his fearsome qualities, the Slender Man is often affectionately referred to in blogs and chat groups as "Slendy," much like another demon du jour making the Internet rounds, "Masky."

The Slender Man has similarities to previous frightening entities like the Tall Man from the '79 cult classic film "Phantasm," so it's hard to pinpoint when the legend began. Slendy's breakout moment came in 2009, when contributors to a forum on the Something Awful website began photoshopping his menacing form into the background of otherwise-innocent scenes. Then, some pranksters taped a series of impressive YouTube videos called “The Marble Hornets,” telling a "Blair Witch"-style story in which the threat of a Slender Man confrontation looms, now out on DVD.

"Whenever I watch those videos online I go to sleep with my TV on for the next two days," Hughes said. "When you don't know exactly what something is, your own mind can freak yourself out."

He recently saw that theory in action when his friend Natalie Hanley, who hadn't heard of Slendy until he showed her some of the videos one night, pooh-poohed the sinister beanpole -- at first. But the next day, Hughes got a wee-hours text from her saying that she, too, was having unsettling thoughts.

"I didn't think much of it at first," said Hanley, a senior at St. Anthony Village Senior High. "But when I got home that night, my parents weren't there and the house was dark. I looked up at our tall ceilings and thought, oh no, Slender Man is really tall, he could fit in here."

Horror blogger Van Fleet writes that these kinds of feelings are "silly, yes, but, after we wake from a nightmare, and the stars are still out, aren't there at least a few seconds where boogeymen (and slender men) feel as real as anything else?"

Kristin Tillotson • 612-673-7046