Baba Yaga

Baba Yaga is the most famous figure of Russian folklore and mythology, hands down, being the only character anyone who isn't Russian can probably name. A hag's hag, Baba Yaga varies wildly between different stories from standard child-eating ungodly abomination to a chaotic trickster mentor, who can be both ally and enemy depending on her mood and how much respect you show her. Some of the few things that remain constant; she flies in a mortar and pestle, she has a sweet-ass house that moves by walking along on giant chicken legs, and you do not fuck with Baba Yaga.

Baba Yaga has warranted occasional mentions in Dungeons & Dragons; for example, the infamous witch of Greyhawk, Iggwilv, is rumored to be one of Baba Yaga's daughters, whilst she was instrumental in creating the Demon Prince Kostchtchie.

However, it is in Pathfinder that she has truly shone, as Pathfinder has no shame about stealing from real-world myth and folklore to pad out Golarion. Baba Yaga is a huge plane-travelling "Mover and Shaker" type figure, despite coming from humble stock as a Middle Ages Russian peasant girl whom a powerful faerie taught the arts of sorcery for shits 'n' giggles. 1400 years ago, she came to the land of Irissen and took it over with a legion of trolls, giant wolves, Frost Giants, and evil Fairies. She locked the entire country in an eternal winter, left one of her daughters(there's a scary thought) on the throne, and every one hundred years, she collects said daughter and all her children, and puts another one on the throne to rule for another century. She is the star of the "Reign of Winter" adventure path, which lays her entire history and power set bare in its final issue.

The vampire version of Baba Yaga also appears as a horrendously powerful Nosferatu methuselah in White Wolf's World of Darkness. She created the magical Iron Curtain that caused the rest of the supernatural world to be cut off from Soviet Russia during the Cold War while she did bad things to those inside. A charming specimen, she was an eight foot tall vampire with iron claws, iron fangs, skin covered in pustules, and a stereotypical long crooked nose. She was later killed by another childe of her sire, a Nictuku (scary Nosferatu-hunting vampire) that took the form of a small girl by the name of Vasilisa. If this sounds like a certain Russian fairy tale, you're paying attention.