Umar first appeared in Marvel Comics' Strange Tales #150, in a Doctor Strange story written by Roy Thomas, and illustrated by Bill Everett under the editorial eye of Stan Lee. In the final panel of the previous month's Strange Tales #149 (written by Denny O'Neil), however, her debut appearance was foreshadowed under a different name.
"NEXT MONTH... The dramatic defeat of Kaluu
-- and the introduction of the intriguing and totally unforgettable villainess of all time -- KARA Can you afford
to miss it!"
The cover of #150, however, ran the teaser "Exit Kaluu... enter Umar!" with her initial rendering. Appearing within on the final (tenth) page, Umar then spends most of issue #151 as a narrative tool, recapping the events which occurred during her banishment, for the benefit of the returning and new reader alike.
Umar and her brother Dormammu were spawned in the Faltine Dimension 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, the siblings 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 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, 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.
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 had a tryst 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.
In time, Dormammu tried to invade Earth's dimension and came into conflict with first the Ancient One, and then Doctor Strange. Eventually Dormammu was defeated, and the spell banishing Umar was broken. Umar was able to stop the invasion of the Dark Dimension by the Mindless Ones, and became ruler of the Dark Dimension. 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 showed Umar an image of Umar's original Faltinian visage. This sight drove Umar almost to madness, and she traveled to Earth to destroy it in revenge. There, she battled the Ancient One. Strange defeated her by summoning another monster; Zom, forcing her to flee. Umar later freed Doctor Strange, enabling him to defeat Dormammu.
Umar attacked Doctor Strange and Clea on Earth, and transported the essence of Dormammu to Earth's core, where he reformed. With Orini, Umar defeated Doctor Strange on Dormammu's behalf. With Dormammu, Umar battled the Scarlet Witch, Vision, and Agatha Harkness. Umar's seduction of Orini resulting in the birth of Clea was then recounted. Umar stole Dormammu's power, using it to battle Doctor Strange and Clea. Umar was defeated when Gaea caused Dormammu's power to return to him. Umar later battled Thor in an attempt to disrupt a chess match between Odin and Dormammu.
Umar later intervened in Doctor Strange's battle with a deranged Black Knight. She conjured a sea serpent and water elementals to attack Doctor Strange and the Black Knight on Earth. Umar's origin was finally recounted, and the secret of Clea's parentage was finally revealed to Clea and Doctor Strange. Umar was then deposed as ruler of the Dark Dimension by Clea, and with Orini, Umar was banished to an alien dimension by Doctor Strange and Clea.
Dormammu returned to overthrow Clea, and freed Umar from banishment. 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 divide 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.
Umar was separated from Dormammu again, although the siblings retained a mystic link, and the two collaborated in defeating an avatar of Eternity, and using the acquired power to remake the universe in their hellish image, but she eventually betrayed her brother, stole his power, and trapped him in the form of a powerless crippled mutate.
When Dormammu's minion, criminal gang-leader The Hood, questions Satana to learn about his master, the demoness refers to Umar as having been killed by her brother.
Umar is later resurrected along with other villains by the magic of the Wishing Well.
Umar has a gifted intellect, and vast knowledge of magical lore. She has tremendous ability to manipulate the forces of magic for virtually any effect, 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.
Umar in her human form is a featured "boss" in the Spec Op 30 of Marvel: Avengers Alliance.