Doctor Stephen Strange didn't go looking to be a hero. In fact, his motivation to become a sorcerer comes from his obsessive desire to cheat the biology of his injured hands. But his motivation to become a superhero is developed almost by accident, thanks to the villain Kaecilius and his evil plan to destroy the planet. Also known as a Zealot, Kaecilius is a fellow sorcerer, who abandoned the Ancient One to pledge his allegiance to the Dark Dimension's Dormammu. Though he is a much more experienced sorcerer than our dear Doctor Strange (spoiler alert), he fails in the end and is absorbed into the Dark Dimension. In the end, it looks like he isn't just defeated, he's dead, but is Mads Mikkelson's Kaecilius really dead in Doctor Strange ?
Kaecilius meets his end after Doctor Strange pushes him and the other zealots into the Dark Dimension opened up by Dormammu. We see Kaecilius slowly disintegrate, literally, as he's drawn out into space, suggesting that the Dark Dimension has dissolved his being. But, we all know better than to believe what we see, especially after the mind-bending visual twists and turns of Doctor Strange . Not to mention the fact that Kaecilius was driven by the belief that Dormammu would give him eternal life. For all we know, Dormammu followed through, even if it wasn't exactly the way Kaecilius envisioned. Until it's all said and done and this phase of the Marvel Cinematic Universe is over, it would be foolish to assume that Kaecilius is gone for good.
Should Kaecilius return from supposed death, he might not be the same sorcerer we remember. There is a theory that Kaecilius' death is actually a Marvel Easter Egg, planting the seeds for the introduction of the Mindless Ones. When Kaecilius' being disintegrates, there is a gleam of light that emerges. It could just be an effect for the sake of dramatizing his death, or, as suggested by MoviePilot, it could be a sign that he was being turned into a Mindless One.
In the comics, the Mindless Ones are powerful, almost invulnerable beings, characterized by large, thick bodies and a purple rectangle where eyes would be. The purple around the eyes, of course, was also used to mark the Zealots in Doctor Strange. The Mindless Ones can't think for themselves, and are instead controlled by Dormammu in the Dark Dimension. If Kaecilius did survive the ending of Doctor Strange, odds are he's now a Mindless One, which means he's pretty much dead anyways. Mindless Ones are not people with thoughts or desires, they are a mindless herd of killing machines. If Kaecilius is alive as a Mindless One, his soul, for all intents and purposes, is dead.
Regardless of Kaecilius' fate, it's likely that Mikkelsen signed a contract that included the option for multiple MCU films. So, I wouldn't count Kaecilius out for good. Dead or alive, he could always return in flashbacks, short films, or post-credit scenes. You never really know when or where Kaecilius may pop up.
Images: Walt Disney Studios; infiniitywars/tumblr; beaufortplace/tumblr
