9. Benedict Cumberbatch - Dormammu
Despite having such a small amount of screentime, Dormammu is without a doubt the most powerful character seen throughout the entire MCU, Thanos included. A metaphysical being, he appears only at the end of Doctor Strange, but his presence was felt throughout its entire narrative.
As with any other God-like entity he naturally has his followers to carry out his will, the Zealots who were lead by Kaecilius. They may have dutifully performed their master's bidding in his attempt at ruling the Multiverse, but it is his inability to enter our universe which is Dormammu's Achilles heel.
As such, Doctor Stephen Strange M.D., PhD. must take the fight directly to Dormammu himself in order to vanquish his threat once and for all, and in such a metaphysical final showdown it is no surprise that Benedict Cumberbatch also played his part in bringing Dormammu to the screen as well as Dr. Strange.
Although his defeat was hardly surprising, the fact that it comes due to an equally beneficial arrangement adds a neat narrative twist, but does nothing for his street cred. Even in his native Dark Dimension the source of all his nigh-on unlimited power is worth absolutely nothing when compared to an ego that just won't take no for an answer.