Entity 6, commonly cited as Dullers, are infamous entities who reside in a plethora of levels within the Backrooms. Dullers tend to flourish in dim, rural areas in which outside interference is unlikely. These entities are very hostile and should be avoided at all costs.

Dullers take on the appearance of long and dark humanoid-like beings with no humane facial features; nonetheless, some concave cavities may mimic deformed eyes and mouths, usually representing that of a melted face. It is unfathomable how they can see, smell, or hear, as it has been demonstrated that Dullers can traverse their environment flawlessly, unaffected by darkness or any other variables that would normally impede one's vision.

Although each Duller may differ slightly in size, shape, and behavior, they are usually identical. Entity 6's skin is dark and wrinkled, occasionally ripped or "boiled", revealing purplish flesh beneath, some parts being twisted or mangled in unnatural demeanors; additionally, Dullers are physically stronger than most wanderers, being able to rupture bones with ease; along with this, Dullers are highly intelligent beings who enjoy tormenting their victims via psychological torture or auditory and visual hallucinations; the effects caused by Dullers can be correlated to post-traumatic stress disorder as they are somewhat similar to one another. These sessions of torture are prolonged to hours, in which, to prevent their victim from fleeing if broken out, they incapacitate the wanderer. Afterward, said victims are slained brutally.