Baba Yaga is a villain of Hellboy she is based on the witch of the same Russian Folklore.
Baba Yaga's history is mostly the same as her Russian with some alterations to fit in with the Hellboy universe
Ages ago Baba Yaga took advantage of Koshichi fear of losing his soul. She told him that even though the path he took was dark and bloody, but he could still be redeeme
In the Present timeline of the Hellboy series Baba Yaga would encounter Hellboy due to kidnappping and eating Children. Then in Wake the devil Baba sends her servants to help Rasputin after he failed to save Ilia'soul to survive the apocalypse.
Baba Yaga will appear in the upcoming Hellboy movie in 2019
Powers and Ablities
Baba Yaga is a very powerful witch possesing all types of magic