Proxy

Proxies are entities or people who are under the influence or control of the Slender Man (or similar entities), and act based on its wants/needs; hence, Proxies serve as an in-between (a proxy) for the Slender Man.

It is suspected that Proxies do the actual, physical work for Slender Man, such as creating and manipulating objects, destroying and leaving evidence, creating videos and responding on Twitter, and influencing victims as needed.

Initial Influence and Origins
Proxies most likely got their start from early Slenderman works' usage of mental influence of Slenderman. Early creepypasta indicated that Slenderman was able to telepathically communicate or influence his victims or those he wished to do his bidding. The most common early evidence for this was the usage of telepathic communication to speak to children who he would lead outdoors and then into the forest. He also used the telepathy to control his victims without their knowing and bring them into his domain. Several stories in particular focus on the strength and usage of this power. The idea behind proxies may be derived from the idea that he could not only influence his victims, but also influence individuals to do as he wishes to get to his victims. Proxies are considered the primary or secondary antagonists of most Slenderman based ARG's.

Proxy Types
There are many different kinds of Proxies under the control of the Slender Man.

Revenants: The dangerous Proxies, who have similar abilities to their master, although not as powerful.

Agents: People who willingly choose to obey the Slender Man without the need for control or torture.

Sleepers: These people are only controlled by Proxies when there are minds are weakest. Another name for these are Vessels.

Bezerkers: Under the control of the Slender Man, but are not directly ordered by him. These Proxies are able to gain your trust easily and are then able to manipulate you.

Excerpt: A Proxy whom is only partially controlled by the Slender Man, and has periods where he has free will. Not to be confused with Sleepers, for these are no longer humans.

Proxy Hunters
People or groups who try to hunt down Proxies for various reasons. Typically, these are people who have been damaged (emotionally, physically or mentally) by the Slender Man or one of his Proxies, and want to have revenge, or simply dislike the Slender Man and/or his Proxies.

Symbols and Markings
Each proxy appears to have some kind of symbol of their own.

If not, they sometimes share the marks of  others. It's unknown what each mark means; Whether they have an actual paranormal or physical use, or  simply a symbol of Slender Man's repeating presence.

 The Operator Symbol has been seen in many Slenderman ARGs,  but it has been accepted as the primary  pop culture symbol for Slender Man and Proxies.

Relation to this Reality
Choices, a very important part of these events, has confirmed that he was a Proxy for the Slender Man, but now takes orders from the Guardian. He coined the phrase Excerpt, referring to himself.

Vision also said that he was a Proxy, but since he has not been heard from for a long time, his current status is unknown.

W-Man and Matthias started to show Proxy-like characteristics before they left the Slender Finders, i.e. bouts of insanity, an alternate personality, and murderous tendencies. Matthias was confirmed to be a previous vessel of Choices