Chernabog is a giant nocturnal demon that is the main antagonist in Night on the Bald Mountain. He is a massive, black, horned and winged demon. Chernabog is a name from Slavic mythology that means "Black God". He features in Disney's Fantasia as the controller of masses of ghosts and undead.
Much has been speculated about Chernobog, but little can be said definitively.The only historical sources, which are Christian ones, interpret him as a dark, accursed god, but it is questionable how important (or evil) he was really considered to be by ancient Slavs.