The Leshy in Slavic tradition is the king of the forest. He often appears as a normal man, but he is a changeling, and can change his form and height at will, being as small and thin as a blade of grass, or as large and imposing as a tree—in fact, he can turn into a blade of grass or a tree, if he so chooses. Leshies are also supposedly responsible for mass migrations of animals in the forest. In other places he is described as having blue skin and green hair and a green beard, but in many stories he looks simply like a peasant with shoes on backwards.
Leshies are mischievous creatures, likely to hide the ax of a wood cutter, or make a traveler lose their way in the forest. The only way to escape once a Leshy has doomed you to being lost is to turn your clothing inside out and wear your shoes on their opposite feet. Leshies do make pacts with farmers and shepherds, though, and will teach a person its magic if you befriend it, which you can do by handing it a cross from around your neck. That said, they also imitate voices of people a wanderer knows, in order to lure them back to their caves and ultimately tickle them to death (yes, you read that right). If a forest has more than one leshy, the two will fight for dominance, which may result in fallen trees or scared wildlife.
Possibly the most effective way of getting away from a Leshy is to set the forest on fire and run—he’ll be so concerned with what’s happening to the forest that he’ll forget about you, most likely. This, however, is highly illegal and dangerous, so we recommend you just don’t run into a Leshy in the first place.