Our favorite faceless stalker. He's taken an interest in three people living in a house, and the results are not pretty.
Big Bad: He's a lot more hands-on than the typical depiction; the entirety of the conflict falls squarely on his shoulders.
The Bad Guy Wins: As long as you live, he always wins. And of course, if you die, you lose.
The Blank: He lacks a true face, for sure, but images in The Arrival show that he does have something, at least. We can't tell if they're wrinkles, scales or scars, or some deranged combination of the three.
Foreshadowing: Pictures of him are drawn on the walls and in some notes found in Kate's room. If you turn on the radio after getting the flashlight, you can actually see the man himself standing outside a window, before teleporting away.
Infectious Insanity: Heavily implied in Arrival that his entire existence depends people knowing he exists - and people who go insane tend to go to great lengthsto let other people know, willingly or not. In fact, it's implied in the hard mode ending that he saved Lauren specifically so he wouldn't vanish, and/or to make sure she continues spreading knowledge of his existence.
Those who are unfortunate enough to succumb to Slender Mans influence become his proxies and hunt his next victims for him.
Lean and Mean: One of the more chilling portrayals, given what he puts Kate, C.R. and Lauren through.
Offscreen Teleportation: Whenever you're not looking, which will be most of the time since you can't actually stare at him for too long in this game without getting a Game Over.
Occasionally he'll teleport while you are looking. Hoh boy...
Right Behind Me: Constantly, after you've gotten up to six pages. From that point on, he'll be on you like a bloodhound!
Was Once a Man: Subverted, actually. There appears to be a connection between him and Charlie Matheson Jr. (the latters' poster combines with the Slender Man in the secret level), but there's the implication that Charlie is actually CR, so it's very likely the Slender Man was only trying to Mind Screw Lauren again.
The female protagonist of the second game. Her car is parked at the head of Kate's driveway, as it was stopped by a fallen tree. She goes searching for her missing friend Kate and uncovers various pages written by her other friend, CR.
Ambiguous Situation: Her final fate is left unclear, even in the Hardcore mode. For all we know, the camera could've just been kept on by that point.
Featureless Protagonist: Subverted in that it's fairly obvious that you're controlling Lauren, the only other named character from the writings.
Not Quite Dead: The game ends as she is trapped in a room with a drained flashlight and someone (or something) opens the door to attack her. In Hardcore mode, it seems that she survives... but only because it's in the Slender Man's best interests that she lives.
In the Steam version, she was taken to some dark house by a proxified Charlie. Once Charlie leaves the premises, Lauren goes up the stairs and sees Kate back to her human form, but with image distortions all around her. Lauren walks up to her... and get mauled at by a now-proxified Kate. The camera pans to her lifeless legs on the floor, just before her body is dragged away by either Kate or Charlie.
Silent Protagonist: Zigzagged. If you go to the swings on the first level, before entering the house, subtitles pop up. They say "I remember playing on this swing-set with Kate when we were kids". It's the first clue that you're playing as Lauren, but you never hear spoken dialogue.
Another set of subtitles occur when you see the missing poster. They say "I should keep an eye out", but she never speaks them.
The recipient of several notes found throughout the game and the owner of the house that the prologue takes place in. Lauren spends the game searching for her. At the very end of the first level, you could hear a high-pitched scream in the woods, which presumably belonged to Kate. Has become a Proxy for the Slender Man, attacking the player at a couple of points in the game.
Rogue Protagonist: CR mentions that Kate was once found unconscious in a park with strange drawings and a broken video tape, implying that she may have been the protagonist of the original game.
Sanity Slippage: She used to go out ghost hunting with CR back in their childhood. At one point, they started hallucinating, and she was found in a park with a broken video camera, a flashlight and a stash of 8 pages. She was taken to a psychiatric ward, where she was deemed stable and free to go, but it all fell apart since.
Silent Protagonist: Subverted. In the flashback portion in the Arrival where you play as Kate she talks to her camera, saying to shut all the doors and windows. Leaving her room to do that doesn't really work out well for her. The only thing we hear from her after the point of the flashback is her scream coming from the woods at the beginning of the game.
The sender of several notes found throughout the game. A close friend of Kate, who is also being victimized by the Slender Man. Lauren passes another car on the way to Kate's house, which we assume belonged to him.
Ambiguous Situation: Why is he called CR? Perhaps he's actually Charlie Matheson, the kid in the missing poster?
Driven to Suicide: Strongly implied. He leaves several notes declaring his desire to die and is latter found as a charred corpse in the ending
The Ghost: Doesn't appear in person, although his unrecognizable dead body is discovered in the ending.
Friendless Background: It's implied that CR is the boy whose missing poster reads "Charlie Matheson Jr." Having apparently left his family, he played in the woods with Kate as a kid and sneaked into the Kate's house all the time. He stopped visiting once Kate's mom caught wind of it. He knew about Lauren, but specifically asked Kate not to tell Lauren about him. Kate was his only real friend by this point.
Kill 'em All: Based on his writings ("It has to end with you" to Kate and his refusal to let Lauren know of him), it appears that he feels everyone who knows of the Slender Man must die. It explains part of why he burned himself to death.
Kill It with Fire: White chalk on a rock reads "End it with a fire." His charred corpse is found in the finale scenes, possibly by his own hand.
A boy found in a missing wanted poster. In the Steam version, it's revealed that Charlie's father committed suicide after Charlie went missing, and C.R. was trying to help out the Matheson family by looking for him.
Jump Scare: In the Steam version of the Prologue, if you walk around in the woods, you can find an abandoned wooden house. Enter it and you'll see a blue-ish, shirtless and deformed humanoid twitching from side to side as it looks to the wall. This is Charlie, or at least what's left of him. If you go near him, he'll lash out at you, flashing the same blue human images that can be seen in the final level.
At the Steam version of the final level, when you see C.R.'s corpse, Charlie's figure can be seen running straight at Lauren. It's rather jarring, as it's never been seen before in any other version.
Mind Screw: If you keep clicking on the missing poster, you'll get wrapped in a bizarre, fucked up version of Kate's house.
He caused the same for his father. Charlie Sr. keeps thinking that he sees his son staring at him and giggling like a kid at times.
Non-Malicious Monster: Despite being an emaciated, corpse-like being (presumably due to the Slender Man), he actually kept Lauren alive and guarded the stairs to keep her from seeing a Proxified Kate at the top floor.
Was Once a Man: The Steam version of The Arrival reveals that Charlie was turned into a Proxy by the Slender Man.
A human found in the generator level. It chases you down along with the Slender Man when you activate the generators.
The Reveal: It's strongly implied that Kate is the Chaser.
Samus Is a Girl: The jacket, the hood and the mask all make the Proxy appear rather masculine, when in reality, it's Kate.
Weakened by the Light: No wild howling induced by it, but they will be seemingly stunned for a bit if you shine your flashlight in their face. Doesn't make them harmless by any means though. Get too close and you still get jumped.