According to a rumor from Heroic Hollywood, Mikkelsen -- whose role has been kept a secret -- is in fact playing Kaecilius in the film. Mikkelsen previously teased his character as "Not really a baddie, but someone who believes in something else than what Doctor Strange believes in."
HH previously indicated that Kaecilius would be the main villain in the film, though that's yet to be confirmed. In the comics, Kaecilius is a disciple of Baron Mordo who first appeared in Stan Lee and Steve Ditko's run on "Strange Tales." The character went on to appear in an issue of "Doctor Strange" by Roger Stern and Paul Smith in 1982. He hasn't shown up in a comic since.
The site points to an upcoming mini-mates set tying in to the film that includes Mikkelsen and Chiwetel Ejiofor's characters sold as a pair.
Marvel Minimates Series 70 Doctor Strange Movie 2-Pack Asst.
A Diamond Select Toys Release! The next chapter of the Marvel Cinematic Universe is now the next entry in the long-running Marvel Minimates line! Series 70 of Marvel Minimates mini-figures travels to the world of the Doctor Strange movie, with four different two-packs: Dr. Strange with The Ancient One, Mordo with Kaecilius, the specialty-exclusive Stephen Strange with Christine Palmer and the specialty-exclusive Wong & Zealot! Each 2-inch Minimates mini-figure features 14 points of articulation and fully interchangeable parts. Each two-pack is packaged in a full-color window box.
Directed by Derrickson, written by C. Robert Cargill and Jon Spaihts, and starring Benedict Cumberbatch, Rachel McAdams, Tilda Swinton, Mads Mikkelsen, Chiwetel Ejiofor and others, "Doctor Strange" hits theaters on November 4, 2016.