One of the biggest mysteries surrounding the Doctor Strange movie has been the identity of its main antagonist, played by Hannibal star Mads Mikkelsen. The teaser trailer displayed some of his power, but who he is and what exactly he wants to accomplish have been kept under lock and key. While an upcoming toy release recently leaked that his name is Kaecilius (who was rumored to be involved last year), now he's been officially identified by Marvel in a prequel comic book delving into what this sorcerer was up to before the events of the movie kick off.
In the Doctor Strange "prelude" comic book's first issue (via Comic Book Resources), we learn that Kaecilius was originally a Master of the Mystic Arts who worked with The Ancient One, Wong and other powerful spell casters. At some point in time, these sorcerers were sent to capture a young woman who stole a mystical staff that appears to be mounted with the Eye of Agamotto, which Stephen Strange will eventually harness. When he tries to subdue this woman on his own, Kaecilius is defeated, but with the aid of the other Masters, he is able to stop her and return the Eye to the Sanctum Sanctorum. Also, unlike the other sorcerers, he is holding a pair of daggers rather than a staff, though whether that's significant remains to be seen. As a bonus, we also see Daniel Drumm, who in the comics is the villainous brother of Brother Voodoo, but here is a benevolent character.
Although Kaecilius in the comics was merely Baron Mordo's minion, it was revealed earlier this year that in the Marvel Cinematic Universe, he was one of the Ancient One's followers until be broke off and formed his own sect. In this prequel issue, we can clearly see that he was a "good guy," though he did display some attitude that hinted at his future abandonment. We'll have to wait until the second issue comes out to either see him leave or learn why he will between this story and Doctor Strange, though it's confirmed it has to do with him disagreeing with how The Ancient One is "protecting her own power base" and not letting certain magical forces into this realm.
Mads Mikkeslen went on record last month saying that he doesn't view Kaecilius as a villain, but as someone who wants to save the world in an unorthodox way. Nevertheless, he'll still be the main antagonist Stephen Strange must face when he learns the ways of magic, and the teaser trailer made it clear he controls powerful, otherworldly forces. Leaked set photos also showed Mikkelsen with weird scaling around his eyes at some point during Doctor Strange, hinting that Kaecilius will be corrupted by a dark power or even possessed by a demonic being, like perhaps Dormammu.
If you want to read this Doctor Strange comic issue for yourself, you can find it at your local comic book store or digitally at Comixology. The Doctor Strange movie will cast its spell in theaters on November 4.