As the production for Avengers: Doomsday moves ever closer to starting production, MCU fans are starting to learn more and more about what they can expect in the upcoming film. Of course, long before Avengers: Doomsday got anywhere close to shooting, the biggest surprise of all was revealed in who would play the main antagonist. Needless to say, there were more than a few people who were truly shocked by Robert Downey Jr. returning as Doctor Doom.