Dweller in Darkness

As far as magical beings are concerned, few can challenge Dweller in Darkness and actually win. This Fear Lord not only created D’Spayre, but is one of the most powerful of his kind (after all, he assembled the Fear Lords for the first time), being able to transport himself into Nightmare's dimension without the fear of repercussions (there aren't that many Marvel characters that can fight Nightmare in his own dimension).

While he has clashed on various occasions with Doctor Strange, the Dweller in Darkness doesn't really like to get his hands dirty. As such, he is capable of creating powerful minions who actually pose real threat to the Sorcerer Supreme. The minions that he created are so strong that they actually stood a chance against the combined forces of Thor and Hercules, fleeing only after the sun rose.

As a matter of fact, the Dweller has so much power that he could crush Stephen Strange if he wanted "“ however, as he doesn't see this as his purpose/goal, he simply doesn't. After all, Agamotto (the first Sorcerer Supreme and one of the source of Doctor Strange's many powers) managed only to imprison and not destroy him.