A human shadow, allegedly what the Flat Man looks like.
Flat Man is allegedly a creature living in Yakutia, a remote part of Siberia, described by a 4chan poster living in Yakutia.
Description[]
The Flat Man is a creature that resembles a living human shadow that only moves on the ground. It can suck victims inside of it once they enter the shadow, like a black hole. The local populace fears it, and is reluctant to talk about it, even engaging in fights with people who bring it up. One story describes the creature consuming an entire house.
According to the 4chan post, the Flat Man is an ancient creature, that allegedly consumed entire tribes in Yakutia.