Maahis

In Finnish folklore, there are creatures that come from the underworld, but prefer to live in the forest. They are considered his masters.

They are described as humanoid creatures of small stature with some small external deformities, for example, a hump or a backward-turned foot. Maahis can confuse the traveler and lead him astray (to prevent this from happening, you need to turn your clothes inside out). You cannot spend the night in the forest or build a house without Maahisa's permission.

Finns bring treats for a safe overnight stay or bury a coin in the ground, buying land from a dwarf (if this is not done, he can steal cattle or a child, replacing it with his own).

They are short and ugly, but they can have beautiful daughters. These creatures are werewolves: they can take the form of various forest animals.

In their underground world, creatures walk upside down on the ceiling, i.e. the reverse surface of the earth. A person who somehow got into this kingdom should not taste their food, otherwise he will not return to earth or, upon returning, will find that a year spent in the underground kingdom is equal to several decades on earth.