[2][3][4] He is the extra and inter-dimensional demonic entity and deity brother of Umar and the uncle of superheroine Clea who rules over the Dark Dimension.

[7][8] Dormammu has appeared in associated Marvel merchandise including films, animated television series, toys, trading cards, and video games.

Writer Mike Conroy said: To Lee and Steve Ditko, the Lord of the Realm of Darkness and the associated invocations were just another piece of business, another way of adding depth to the otherwordly [sic?]

Secretly in the entity's service, Mordo attempts to slowly weaken the Ancient One as a means of enabling Dormammu to finally extend his rule to Earth, but is stopped when his fellow pupil Stephen Strange alerts his master to the betrayal.

Dormammu engages Strange in mystic combat and shows himself to be far more powerful, but, when drawing upon the realm's energies, inadvertently weakens the barrier containing the horde of Mindless Ones.

[14] Dormammu uses a loophole to his oath by granting Mordo vast power, whereupon the sorcerer leads his minions on a lengthy hunt for Strange and abduct the Ancient One as a bargaining chip.

Dormammu learns of her betrayal, brings all three Earth sorcerers to a neutral realm, to let her see his disciple destroy Strange, and summons fellow "Lords of the Netherworlds" to watch the spectacle.

[17] Dormammu enters into an alliance with the Asgardian Loki and tricks superhero teams the Avengers and Defenders into fighting each other for components of the artifact known as the Evil Eye.

Together with Umar, Dormammu captures the elder goddess Gaea,[20] and seeks revenge against the Scarlet Witch by kidnapping her and her mentor Agatha Harkness from her wedding to the Vision.

[25] Dormammu's agent Baron Mordo travels back in time to London in the year 1943, where he allies with the aristocrats Viscount Krowler and Sir Anthony Baskerville.

Dormammu possesses Krowler, and begins to manifest on the Earth plane by absorbing power from the destruction of World War II, but he is banished by Doctor Strange.

[27] The character reconstitutes again, regains control of the Dark Dimension from Clea by subverting her will, and summons her parents, Umar and Orini, from exile.

The enraged Dormammu threatens to completely destroy the "Dark Dimension" in retaliation, but Umar convinces him to accept a compromise as the ruler of a sub-realm, whereas his sister takes over rulership from Clea, with Mordo as her consort.

Strange, at the time weakened without support from the "Principalities", confronts Dormammu with his allies Clea, the Silver Surfer, Hulk, and Ghost Rider, but they are unable to cause any injury to the villain.

Strange journeys into the core of Dormammu's essence and uses the Eye of Agamotto to strip away his self-delusion, and make him acknowledge that his thirst for chaos, power, and conquest are unworthy of a being of his stature.

The villain gloats that he has not shown "one tenth" of his true power against the heroes, but that he now realizes that rulership of "one puny" universe is beneath his notice, as he now has far greater and "more interesting" ambitions, and contemptuously dismisses the "insignificant mortals".

Dormammu follows them back to their dimension, merges with his counterpart in this timeline, doubling his power, and attacks their headquarters, demanding the presence of the Doctor Strange of their time.

During The Flight of the Bones storyline the character is revealed as the instigator behind a series of spontaneous combustions of criminals and an attack on an ally of Strange by cultists.

Dormammu, however, is thwarted when the heroine Hellcat rallies the powers of Hell to weaken the character by engineering a complete absence of mystic flame.

The pair are opposed by a reuniting of some of the original Defenders (Strange, the Hulk, and Namor the Sub-Mariner), with Dormammu retreating when Umar steals his power.

[39] Acting in secrecy, Dormammu empowers criminal mastermind the Hood, who in turn resurrects several dead supervillains and forms a crime army.

[48] The entity reappears with a plot to turn humanity into Mindless Ones, but is thwarted by the plans of Phil Coulson, with help from the Absorbing Man and the Howling Commandos.

"[41] It is unknown exactly how ancient he is, as he inhabits a wholly alien realm, separate from the rest of the Marvel Universe, that defies the laws of physics as understood on Earth.

He is known to have already existed at the creation of the current demonic netherworlds;[35] to have clashed with Agamotto hundreds of millions of years ago; to have served as the primary enemy of the Vishanti ever since; and to have been considered an extreme threat by the mages of "pre-cataclysm" Atlantis.

Not native to the "Dark Dimension", Dormammu and "his" sibling Umar were exiled for slaying their progenitor "Sinifer" and for their morbid/unclean obsession with physical matter.

[51] Dormammu merged with the local "Flames of Regency" to further enhance his power, and returned to an energy state, whereas Umar had grown accustomed to physical pleasure.

After imprisoning the horde of marauding virtually unstoppable Mindless Ones, Dormammu enslaved the entire realm and demanded worship as its sole deity.

[52] The character is sometimes shown as incredibly patient, with certain plots to achieve his goals spanning billions of years,[35] whereas others are planned far more recently or even improvised through opportunity.

[31] Although extremely intelligent, with tremendous knowledge of the mystic arts, he is overwhelmingly arrogant, generally does not adapt well to sudden confusion and unexpected developments,[32] and has a tendency to gloat over technically outmatched foes rather than swiftly finish them off.

[15][18][31][44] What makes Dormammu different from other prominent Marvel supervillains is that he has been shown as fully capable of personally defeating cosmic entities, even without external power sources and outside of the "Dark Dimension".