The "Creepypasta" phenomenon represents the modern evolution of urban legends—digital campfire stories born in the dark corners of the internet. This world is a grim, interconnected reality where the laws of physics are often subservient to the laws of horror. At the center of this mythos is Slender Man, an eldritch, faceless entity in a black suit who teleports and uses invisible tentacles to abduct children, inducing "Slender Sickness" (paranoia, nosebleeds, and coughing) in those he stalks. He is the master of the "Proxies," human servants who have lost their minds to his influence.

Among the killers, the most infamous is Jeff the Killer (Jeffrey Woods), a tragic figure who suffered a psychotic break after being burned alive; he carved a permanent smile into his cheeks and burnt off his eyelids so he could "always see" his victims, wielding a kitchen knife and whispering "Go to sleep." Closely associated is Jane the Killer, his vengeful rival who wears a black mask and dress, seeking to end Jeff’s spree.

The "Proxies" include Ticci Toby (Toby Rogers), a dual-hatchet wielder who is insensitive to pain and suffers from violent tics; Masky (Tim Wright) and Hoodie (Brian Thomas), who act as the silent, cold enforcers of the Slender Man’s will. In the digital realm, the entities take the form of "Lost Episodes" and haunted games: BEN Drowned, a malevolent spirit inhabiting a Majora's Mask cartridge; Sonic.EXE, a demonic god who tortures souls in a twisted version of his game; and Lost Silver, a manifestation of grief and death within the Pokémon world.

Other apex predators in this collective include The Rake, a hairless, pale humanoid with long claws that attacks sleepers at the foot of their beds; Eyeless Jack, a cannibalistic being in a blue mask who surgically removes and eats human kidneys; Laughing Jack, a monochrome, gothic clown who lures children into his "Abyssal Carnival" to turn them into gore-filled toys; and Smile Dog, a demonic image of a husky that drives the viewer to insanity unless they "spread the word" by sharing the file.