The witch of the deep forest who flies in a mortar and lives in a hut that walks on chicken legs.
Documented
First ink in a grammar book
The earliest written mention lands in a 1755 Russian grammar's notes on folk figures, centuries after the oral tradition. Afanasyev's great nineteenth-century collections then fixed the canonical tales.
Assessment: Documented publication history, which also proves how late writing caught up with the forest.
Stories
Villain and donor in one skin
In one tale she is the terror at the tree line. In the next she hands the hero the exact token he needs. The fence of skulls with glowing eyes guards a figure who obeys rules older than the stories about her.
Assessment: The duality is the folktale record itself. Ambiguity is not a flaw of the material; it is the material.
Interesting claims
A goddess demoted to a hut
The reading: Baba Yaga is a pre-Christian forest and death figure demoted by church teaching, and the leg-hut echoes raised grave-houses of Siberian forest peoples.
Assessment: The grave-house parallel is real and striking. The goddess demotion is a pattern that fits many figures, which makes it both attractive and unfalsifiable.
Sources and further reading
Lomonosov's 1755 grammar notes, first written mention
Afanasyev, Russian Folk Tales, 19th century collections
Johns, Baba Yaga: The Ambiguous Mother and Witch of the Russian Folktale
Siberian raised grave-house ethnography, for the hut parallel
Worth asking
When a culture retires a goddess, why does it keep her house?