Created by writer Roy Thomas and artist Bill Everett, the character first appeared in Strange Tales #150 (November 1966).

A resident of the "Dark Dimension" of the Marvel Comics multiverse, Umar is a Faltine, a higher-dimensional energy being trapped in human form.

[3] One of Doctor Strange's "most iconic villains",[4] the character has been described as "an unpredictable threat",[5] and "a constantly plotting, wicked woman that would do anything, including betraying her own nigh-omnipotent brother for power".

[8] 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.

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!

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 readers alike.

2) #3 (November 2005), Umar uses her magic to enchant the Hulk in order to seduce him and take advantage of him sexually, but is frustrated that the act of copulation with him lasts only six minutes, and angered when he reverts to his human form of Bruce Banner.

[15] Umar was born a Faltine, a race of immortal beings made of pure magical energy that reside in their own universe.

[7] Although the siblings conquer the Dark Dimension together, battling that realm's defenders weakens Umar, who is relegated to the status of Dormammu's subordinate,[5] and is forced to take the form of a mortal body.

[16] Umar grows frustrated with her status in exile,[16] and after discovering she can return to her original form, she attacks her brother in rage, but he easily defeats and banishes her[5] to a pocket world within the Dark Dimension.

[16] When Doctor Strange later defeats Dormammu during a subsequent encounter, Umar is freed from her exile and takes control of the Dark Dimension, but her rule is temporary.

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.

[35] When Dormammu's minion, the criminal gang leader known as Hood questions Satana to learn about his master, the demoness refers to Umar as having been killed by her brother.

Like her brother Dormammu, Umar's magical powers greatly exceed those of all sorcerers from Earth, including Doctor Strange.

[43] In July 2016, Cat Wyatt ranked Umar #10 on Comic Book Resources's list of "The 10 Worst Enemies Stephen Strange Has Ever Faced".

[10] The scene in which Umar uses her magic to seduce the Hulk in Defenders (Vol 2) #3 (November 2005), only to be dissatisfied with his inability to copulate with her for more six minutes, has been mentioned as among critics as a notable encounter between the two adversaries,[15] with Anthony Avina, citing it for his inclusion of the pair's relationship in Comic Book Resources's 2019 list of the 10 Best Romances Between Heroes And Villains among Marvel characters.

[14] Another Screen Rant contributor, Nicholas Conley, ranked Umar's relationship with Hulk number 13 on that website's August 2017 list of the "15 Superheroes Who Had Supervillain Lovers".

Contributor Marc Buxton included Umar, whom he named as the "nastiest" of Strange's enemies, comparing her to Cersei Lannister of the Song of Ice and Fire novel series.

Buxton observed that while Dormammu represents raw power, Umar exhibits "guile and malevolent intelligence" and suggested that making her a film's antagonist would provide for an "epic" story.

[7] In March 2019, Ben Sherlock, writing for Comic Book Resources, included Umar in that website's list of "9 Powerful Doctor Strange Villains We Hope To See In The MCU".

Sherlock also pointed out that this would increase address the dearth of female villains in the series, and that setting such a story in an otherworldly realm would avoid the question that occurs in MCU solo movies of why the protagonists do not contact their Avengers allies for assistance.

[3] That same year, Marvel Studios producer Kevin Feige stated that glimpses of the Dark Dimension would be a part of the plot to that sequel.