Chernobog in Slavic mythology
can literally be translated to The "Black God." He is the God of the night
, evil luck
and infernal darkness
His complete opposite is Belobog (The White God).
You might remember this feller from Modest Mussorgsky's A Night on Bald Mountain in Disney's Fantasia.
Also transliterated as Chernabog, Czernobog, Tchernobog.