Baron Mordo

Baron Mordo (real name: Karl Amadeus Mordo) is a major villain in the Marvel comics universe. He is a powerful and evil sorcerer whom happened to be Ancient One's former pupil until he attempted to assassinate his mentor but is foiled by the new apprentice Stephen Strange, leading to Baron Mordo being cast out and Dr. Strange eventually becoming "Sorcerer Supreme." Mordo would clash with Dr. Strange on a multitude of occasions, at times with the backing of the demon Dormammu, going so far as successfully impersonating Dr. Strange for a short period of time.

History
Originally a Transylvanian nobleman (born in Varf Mandra), Baron Karl Amadeus Mordo became a student of the Tibetan sorcerer known as the Ancient One. When Mordo plotted to kill his teacher, the Ancient One's visitor Dr. Stephen Strange learned of the plot, forcing Mordo to cast restraining spells to prevent him from warning his master or attacking him. However, Strange selflessly decided to accept the Ancient One's offer to learn magic in order to help the old man, and the Ancient One freed him from those spells, revealing he was fully aware were in place. The Ancient One trained him as a formidable enemy of Mordo and Mordo was exiled by the Ancient One.

Mordo later entered service to one of Dr. Strange's enemies, Dormammu, the Ruler of the Dark Dimension, becoming his emissary.

Power and Abilities
Mordo's abilities were similar to those of Doctor Strange, but Mordo was particularly skilled at astral projection and hypnosis, as well as mesmerism. He was more than willing to use powerful black magic and invoke demons, both of which Strange was reluctant or unable to do, although both acts would sometimes backfire on Mordo.

TV appearances

 * Mordo, was a recurring villain in the Spider-Man Animated Series as an enemy of Spider-Man and his ally Dr. Strange. He was voiced by Tony Jay (who is known for voicing Shere Khan, Monsieur D'Arque and Judge Claude Frollo). A former student of the Ancient One, he attempted to overthrow him but Stephen Strange discovered his plan and attempted to warn the Ancient One but Mordo used a spell to silence him. Fortunately the Ancient One already knew of Mordo's plan and effortlessly stopped it, banishing Mordo from his tutelage and taking Strange on as his apprentice. Mordo goes onto become high priest of the Dread Dormammu whom he seeks to release from the Dark Dimension. He controls a cult of worshippers whom he keeps under his control by casting illusions that delude them into believing that they are being reuinited with loved ones. Mordo pursues the powerful Wand of Watoomb, brainwashing Mary-Jane Watson into becoming a member of his cult, showing her visions of her father. When Peter Parker comes to rescue her, Mordo brainwashes him by showing him visions of his deceased parents. He then sends his puppets, including Peter to raid Strange's temple and bring him the Wand of Watoomb. Using his Spider-Powers, Spider-Man overwhelms and his assistant Woo with the help of the other cultists. Mary-Jane makes off with the Wand but Strange captures Spider-Man and releases him from Mordo's mind-control. They then go to Mordo's temple where he is using the Wand in a ritual to open a portal to the Dark Dimension. Spider-Man gets the Wand off Mordo whilst Woo fights off the cultists. Mordo attacks Strange but proves no match for him. He pleads with Dormammu for help and Dormammu sends his servant some of his own powers from beyond the portal. Spider-Man jumps through the portal to fight Dormammu and is joined by Strange. They retrieve the Wand from Dormammu and escape, by which time Mordo has fled.

Doctor Strange: Sorcerer Supreme
Baron Karl Amadeus Mordo is the secondary antagonist of the animated television movie, Doctor Strange: Sorcerer Supreme. Depicted as a fierce warrior, he and his fellow students are shown pursuing demonic beasts through downtown New York. Mordo however, is more concerned with killing the monsters than in actually protecting innocent civilians, causing more damage than the monsters themselves in his pursuit of them. This particulary shown where he, against Ancient One's suggestion to killed nearest Chinou (a species of invading demonic monster where at that time, two members of their kind sent for Sanctum Sanctorum) by divided his team into two groups so they can simultaneously killed two beast, resulting many of his friends got killed. Although a good fighter, he is pompous and not a particularly skilled sorcerer and his fellow students regard him with a mocking contempt due to him seeing himself as leader and his recklessness and lack of concern about their well being. He believes that he will be chosen as the Sorcerer Supreme, but the Ancient One denied it, saying that he never even contemplated him for the position (particulary for his recklessness that killed many of his friends when fighting Chinous) and feels Dr. Stephen Strange is more worthy in such position due to the doctor never obsessed with it. He instead giving him the task of training Strange in the art of combat.

When trained Stephen, Mordo took his anger on Stephen whom just learned how to use magic. In spite of his injured hands newly restored with his own sorcery through Ancient One's guidance, Strange was no match for Mordo, whom goes to killed him out of frustation. However, that's the moment where Strange realized that his skill in magic far superior than he believed: He discovered that he can absorb other's magic and turned it against them. Thanks to it, Stephen managed to defeat Mordo albeit accidently, enraged the disillusioned sorcerer until being stopped by Wong.

Humiliated, Mordo turns to the dark god Dormammu, offering to help him in his plan and Dormammu accepts his assistance. Although Mordo helps Dormammu succeed in entering the world, he is confronted again by Strange who once again effortlessly defeats him. Mordo howls in rage at his inability to defeat Strange before Dormammu, probably feeling embarrassed for Mordo at this point, devours him.

Marvel Cinematic Universe
In Marvel Cinematic Universe, he is played by Chiwetel Efiojor.

Rather than being a villain, Mordo started off as a hero who made his debut Doctor Strange as an ally of Stephen Strange. However, the central antagonist Kaecilius, played by Mads Mikkelsen, does bear some similarities to Mordo, being a former student of the Ancient One who turned to the path of evil.

Mordo eventually becomes disillusioned with the Ancient One's ideals, having witnessed Strange bend the rules of nature to defeat Dormammu. Mordo embarks on a mission to eliminate the other sorcerers of the world, beginning with the Ancient One's former pupil Jonathan Pangborn.