Zmey Gorynych
Zmey Gorynych is the iconic Russian three-to-twelve-headed dragon of byliny and fairy tales. Dwells beyond three rivers or in mountain caves. Each severed head regenerates unless cauterized; kidnaps princesses; breathes fire. Slain by bogatyrs Dobrynya Nikitich and Ilya Muromets. A specific named antagonist, not a species. Name means 'serpent of the mountains (Goryny).'