Much of the Slender Man's fascination stems from the general aura of mystery surrounding him. Although he is rumored to kill almost exclusively children, it's difficult to say whether murder is his sole purpose.

He is often reported or recorded to be found in wooded areas, typically in suburban areas. He has also been seen with large groups of children, as seen in many photographs. It is generally believed that he inhabits forests and copses and preys on children. He seems unfazed by being in daylight or captured in photographs.

He is also often believed to enjoy stalking people who become overly paranoid about his existence, deliberately revealing himself to them to further frighten them. For this reason, the Slender Man appears to derive great pleasure from psychologically torturing his victims.