Baba Yaga

Baba Yaga is the most infamous 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.

Dungeons & Dragons

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. In 4th edition, she graduated to a full-fledged canonical archfey, with her own "Court of Stars" article in Dungeon Magazine #196. Although she doesn't appear in the module, the character of Baba Lysaga from 5th edition's Curse of Strahd is clearly based on her, complete with the walking house.

Pathfinder

However, it is in Pathfinder that she has truly shone, as Paizo has no shame about stealing from real-world myth and folklore to pad out Golarion. Baba Yaga is a central figure of the Reign of Winter Adventure Path, which lays her entire history and power set bare in its final issue. Born on Earth in 75 BC, she managed to become a powerful witch despite coming from humble antiquity Sarmatian peasant girl stock when she was taught the arts of sorcery by a powerful faerie for shits 'n' giggles. As her powers grew over the centuries she became renowned in regional Slavic folktales. She would eventually begin to travel the planes and, about 1,500 years ago, she made a few visits to Golarion before deciding it would be a nice place to put down roots. With an army of ice trolls, giant wolves, frost giants, white dragons and other evil creatures of cold and fey nature, she overran the eastern half of the Ulfen kingdoms. After winning this Winter War in less than a month she carved the new territory into her kingdom of Irrisen, locked the entire country in a perpetual winter, put her eldest daughter Jadwiga on the throne, and then promptly fucked off, a process which repeats every one hundred years. When she returns she collects her daughter and all her children, and installs another one on the throne to rule for another century, and then fucks off again. The only thing scarier than what Baba Yaga does to her daughters once their rule is at an end is what it is like to actually have to fuck Baba Yaga for her to get those daughters in the first place. Occasionally one of Baba Yaga's daughters will attempt to resist being dethroned, knowing that whatever fate awaits them can only be grim, but it generally ends poorly and swiftly for them as Baba Yaga is as wily as she is powerful.

Vampire: The Masquerade

The vampire version of Baba Yaga also appears as a horrendously powerful Nosferatu Methuselah in White Wolf's World of Darkness. Once a shaman and a beatiful young woman, She openly defied Absimilard, a really stronk Antediluvian when she was a mortal, and was persumambly raped and turned into a vampire, then she was made his concubine and one of the Nictuku, already having been blood bonded to that bastard Absimilard. After Caine cursed Absimilard to be uglier than the shit I took yesterday, the curse also went to his childer, making them look like atrocious monsters. After the fall of Second City, she broke her blood bond with no help from anyone, sired the Nosferatu clan(Yes, she takes all the credit related to creation of Nosferatu, not Absimilard. Every Nosferatu that ever existed can trace his ancestry to Baba Yaga.) went to war with Absimilard, who now wanted to kill all his descendants because they are ugly. And she won. Sadly, all she could do was to drive him to torpor, but that is still one hell of a feat. After that, she fell into torpor too, only waking up during Cold War then she created the magical Iron Curtain that caused the rest of the supernatural world to be cut off from Soviet Russia during the while she did bad things to those pansy Brujah commies 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.

She was certainly evil, but held the line against a even more terrible evil, her sire, one of the Antediluvians. That certainly deserves respect.