While Mehrunes Dagon is a more active threat, Molag Bal is by far the more malevolent. He is an evil Daedric Prince whose sphere of influence is domination and enslavement of mortals.
Molag Bal is the overarching antagonist of the The Elder Scrolls franchise, serving as the main antagonist of The Elder Scrolls Online.
~ Molag Bal discovering Mannimarco´s attempt to replace him as a Daedric God Worm! You think you can betray the Lord of Brutality and Domination without consequence? You will pay for your arrogance! You will writhe in agony for the rest of eternity! Your tortured screams will echo throughout Oblivion to serve as a warning to others! Still you fight on? Do you care nothing for your own existence?
Fool! Did you think Molag Bal, the Lord of Domination, would so easily reward you?