Dormammu

"Now come my murdrous minions -- follow in the paths of the Dread One!"

- Dormammu, the Dread One.

Dormammu is a powerful extra-dimensional villain from Marvel most commonly associated with Dr. Strange - being one of the Sorcerer Supreme's most reoccurring and powerful enemies, though he has appeared in other titles as well, most notably Marvel vs Capcom 3 as a playable fighter.

Nature
Established from early on as a warlord from an evil dimension labeled the Dark Dimension he is a creature that seeks universal conquest and has identified Dr Strange as one of the most prominent threats to that goal, for this reason Dormammu has tried many times to destroy the mystic hero but despite his vast power has always failed to do so.

Dormammu often has himself to blame for these defeats however as he often allows his arrogance to get the better of him and he can be somewhat easily tricked by people that know what they are dealing with - of course these flaws may also be the only real things preventing Dormammu from taking over all of reality, given the amount of power he has at hand.

Villains associated with the Dread Dormammu include Baron Mordo, an evil wizard and archenemy of Dr Strange, Umar (his sister) and Satannish, a powerful demon-lord created by Dormammu as an extension of himself - all of these beings have faced Dr Strange on regular occasions and are considerably powerful yet dwarfed by Dormammu himself (even Umar, who is of the same species as Dormammu, is unable to match her brother in raw mystical-power).

Powers and Abilities
Dormammu is nearly godlike in scale, capable of taking on some of the most powerful beings in Marvel continuity and surviving, his power was even great enough to spawn a sentient being such as Satannish and his entire form is made out of raw magical-energy, only serving to boost his considerable power further - he is an object of worship by thousands, if not millions, and the worship he receives also fuels his power and as such he could be considered the most powerful opponent Dr Strange has faced.

Dormammu is composed of pure mystic energy, eclipsing even the greatest of sorcerers in terms of raw power and the ability to manipulate the forces of magic, including Doctor Strange and the Ancient One, which is increased and replenished, at least partially, by worship throughout various dimensions. Among many examples, he is capable of interdimensional limitless astral projection, matter transmutations, interdimensional teleportation, size transformations, elemental control, time travel, projecting energy manifestations ranging from force bolts and cursed conflagrations to magically-constructed beings, changing his appearance, or empowering others to such a point that the empowered one wields power dwarfing even that of a dimension's Sorcerer Supreme. He can draw upon the power of the entire Dark Dimension, but is somewhat more limited when present in another universe.

Dormammu is virtually indestructible and immortal due to his energy form composed of pure magic, and has strength, speed, and stamina, which he can directly empower to levels shown capable of challenging a slightly angered Hulk, or by growing to gigantic size. Dormammu is a capable hand-to-hand combatant, trained in an extra-dimensional fighting style, but was once bested by the well-trained human Doctor Strange when neither was using mystic powers. His chief resources are his tremendous magical powers and considerable intellect.