Thought I might make another list of interesting creature suggestions. This time, I’m going to pull mostly from Slavic folklore.
Ala/Hala: A mix somewhere between a Air elemental and a Demon. The form of this demon is not agreed upon, taking on the appearance of almost any beast, but as an indistinct, hazy cloud. This demon often instigated thunder and hailstorms, which would lead to the ruination of ones crops. It is sometimes heralded by a powerful, resonant hissing sound that comes before dark hailstorm clouds.
https://en.wikipedia.org/wiki/Ala_%28demon%29Leshy: Massive forest spirits. They much akin to the more common tale of the Treant, mixed with a Forest giant. He is known to lead travelers astray from the road, and have the ability to shift his size on a whim. While some claim he is evil, many prefer to think of him merely as a guardian of the forest, like some sort of fae. Not evil, but perhaps tempermental.
https://en.wikipedia.org/wiki/LeshyPersonally, while I think of a treant more like a massive tree that looks vaguely humanoid, I imagine the Leshy to look more akin to a giant or ogre made of greenery, perhaps like certain depictions of Forest Trolls:
https://s-media-cache-ak0.pinimg.com/236x/18/2f/7b/182f7baba9c76dee6953ee90295c62c5.jpghttp://orig09.deviantart.net/0d7b/f/2013/029/a/7/forest_troll_by_collettejellis-d5t579u.jpgRusalka: Water nymph like beings, though sometimes portrayed as more ghost or vampire-like. They were originally relatively benign spirits, though later folklore makes them much more akin to Succubi, tempting men with their beauty towards their watery homes to drown them or steal their essence.
https://en.wikipedia.org/wiki/RusalkaStrzyga: Another type of vampire-like Undead, though this one is a bit more odd. A Strzyga is a person born with two hearts, two sets of teeth, and two souls. It is said that when someone who is a Stryzyga dies the first time, only their first soul dies, and the second soul brings the body back to life. They wander, taking the form of an owl at night, and sucking folks blood and entrails out from them. In some versions of the tale, they are not violent themselves, but appear before people as a herald of death, similar to the mythos behind the Banshee
https://en.wikipedia.org/wiki/StrzygaI was also thinking about adding on Zmey Gorynych, but the slavic dragons really do not have too much that distinguishes them. The only traits that really seem to be somewhat unique is that they have multiple heads (oddly always a multiple of three), and can regrow severed heads like the Lernaean Hydra. Other than that, they are really often just portrayed as somewhat obese, fire breathing dragons.