Proxies are the Slender Man's standard servants, and are commonly described wearing masks and hoodies in order to conceal their identities. In most stories, Proxies are the ones who perform certain physical tasks that the Slender Man cannot do himself because of his inhuman nature. This can include anything from influencing victims as needed, creating and/or manipulating objects, destroying and leaving evidence, and even creating videos and responding on Twitter.
Proxies are typically portrayed as former victims whose mental stabilities have deteriorated considerably after several years of being stalked. This made their minds susceptible to mind control, allowing the Slender Man to influence their thoughts, feelings, and actions through telepathy. Alternatively, some Proxies decide to do his bidding of their own free in order to guarantee the safety of their loved ones or simply because they cannot handle the emotional strain anymore.
Later on, it was explained that there were different types of Proxies:
- Hallowed (or Hollowed): Those whose minds have been destroyed by the Slender Man and placed under his control. They usually behave as mindless puppets utilizing brute force and enter a catatonic state whenever they aren't being used. Their bloodstreams contain the black tar-like substance known as Azoth.
- Berserkers: Those who are under the Slender Man's control but can act on their own when he can't be troubled with commanding them. They will often work their way into positions of trust to further his agenda.
- Sleepers: Those who are under the Slender Man's control but are not aware of it. They lead normal lives for most of the time and never remember what they did under the Slender Man's influence. They are usually Runners who come under his control when their minds are at their weakest, during blackouts or sleep.
- Agents: Those who willingly serve the Slender Man, retaining their original personalities and individuality. Albert Conaghan from Seeking Truth and Joseph Steward from Hidden in the Trees were both Agents.
- Revenants: Those who were granted superpowers by the Slender Man. These powers were later shown to be hallucinations created by Slender Man in order to trick Runners into fighting the Revenants instead of him. The most popular example of a (former) Revenant was Reach from What You Are In The Dark.
Many Proxies appear to have some kind of symbol of their own or share the marks of others. Some have an actual paranormal or physical use, while others are simply a symbol of Slender Man's repeating presence or a means of intimidation. Out of all the markings Proxies have used, The Operator Symbol is the most reoccurring.