The first time I encountered Baba Yaga was via a Mystery Science Theater 3000 episode entitled Jack Frost. (The title of this deviation is also borrowed from one of the protagonists lines.)
She is a nasty old lady riding a mortar and pestle that has a penchant for eating children. (But then what DIDN'T eat children in the fairytale world. It was a pretty everyday occurrence.) Also, she has a cabin with no doors, and no windows, opting to use the chimney to fly out on her escapades. Did I mention the cabin has gigantic chickeny legs?
There are many versions of her, some more threatening than others, but this is mine. :3