Umar

Umar is the twin-sister of Dormammu and like her brother is a powerful demonic creature that seeks conquest, often competing with her brother for position as the ultimate being.

Origins
Umar was spawned along with her brother by Sinifer, a Faltine. The Faltine are beings of pure magical energy that exist in their own universe. It's implied that normally when Faltine spawn, that the new beings are exact copies of the previous, but in this instance, the spawn were different. Unlike Sinifer, they craved physical matter. When Sinifer tried to stop them, they transmuted him from energy into matter, essentially killing him. This angered the rest of the Faltine, and so Dormammu and Umar were exiled from the dimension of the Faltine.

The Dark Dimension
The two fugitive Faltine then entered a universe known as the Dark Dimension, which was inhabited by sorcerers known as the Mhuruuks. Their ruler Olnar dreamed of returning to the days of warfare and conquest. Umar and Dormammu befriended Olnar and played upon these desires. They showed Olnar how to make conquest of other dimensions and bond them with his own. Olnar greedily subjugated several dimensions and added them to his own domain. In time, the rogue Faltines led Olnar to shatter the barrier between his dimension and that of the Mindless Ones. The Mindless Ones were a horde of soulless brutes that exist simply to destroy anything that lies in their path. The Mhuruuks were beaten back by the onslaught and many were slain, including Olnar. Dormammu and Umar then slew or exiled any wizards that might oppose them. Then they barred the Mindless Ones behind a great mystical barrier.

This battle weakened Umar, and she became subordinate to her brother. Dormammu ascended the throne as regent and ruler of the Dark Dimension. He reassumed his Faltinian form of flame, but Umar chose to remain in her human form.

Clea
One of the Mhuruuks who was not slain was Orini, son of Olnar, being just an untrained boy. In time he aged, while the Faltinians remained the same. Eventually Orini became the chief disciple of Dormammu. In time Umar noticed the adult Orini, and trysted with him. Both evidently were virgins, and Umar was initially disgusted with the experience and with Orini himself (she later became a skilled seductress, but her disdain for Orini remained unchanged). In six cycles of the Dark Dimension, Umar gave birth to Clea. This experience changed Umar, and she now was no longer able to return to her Faltinian form.

Her inability to transform angered Umar, and in her frustration she lashed out at Dormammu. Now far stronger than Umar, Dormammu banished her to one of the subjugated pocket dimensions of the Dark Dimension.

Versus Dr. Strange
In time, Dormammu tried to invade Earth's dimension and came into conflict with first the Ancient One, and then Dr Strange. Eventually Dormammu was defeated, and the spell banishing Umar was broken. Despite having been banished by him, Umar sought to avenge her brother on Strange. She held Clea hostage in the Dark Dimension, to lure Strange back in. When she first fought Strange, she was the more powerful, but then the entity called Sayge (aka Veritas) showed Umar an image of Umar's original Faltinian visage. This sight drove Umar almost to madness, and she travelled to Earth to destroy it in revenge. Strange defeated her by summoning another monster; Zom.

After this, Umar performed as Dormammu's subordinate again. She assisted him in his schemes, and helped resurrect him when he fell in battle. While Dormammu was gone, Umar ruled the Dark Dimension until she was overthrown by Clea, who discovered the truth of her parentage during the struggle.

Dormammu returned to overthrow Clea. Clea and Doctor Strange escaped Dormammu, but met with Umar, who wanted to kill Doctor Strange. Umar noticed that her spell was also affecting Clea. Clea revealed that they had been married and that there now was a mystical link between them. Umar stopped her attack and admitted to Clea that she was unable to kill her own daughter. She assisted Strange and Clea in overthrowing Dormammu. Umar tricked her brother by suggesting that they divided the rulership over the Dark Dimension into two parts. Dormammu agreed and Umar banished him to his part: the domain of the Mindless Ones. Umar made peace with Strange and Clea and would now rule the Dark Dimension with Baron Mordo at her side. Clea returned to Earth with Strange.

Many months later, Clea was approached by another Faltine, who claimed to be her cousin. He informed her that she needed to defeat Umar, who had turn into a dictator. Clea returned, but found out that it was a trick: the other Faltine was Dormammu in disguise and he absorbed Umar and Mordo into his own body, growing gigantic in size and power. Clea remained in the Dark Dimension to battle Dormammu.

Somehow Mordo and Umar were separated from Dormammu again, and Umar would assist her brother, though she still had her own agenda. Their most recent exploits are featured in the 2005 Defenders miniseries.

Powers and Abilities
Umar has a gifted intellect, and vast knowledge of magical lore. She has the ability to manipulate the force of magic for a variety of effects, including inter-dimensional teleportation, size transformations, time travel, transmutations, energy manifestations such as powerful concussive blasts, magically constructed animate beings, telepathy, illusion-casting, limited mind-control, etc. As ruler of the Dark Dimension, Umar's head was surrounded by a plume of mystic fire, the flames of regency.