Iron Man

Iron Man did a lot more than just launch the Marvel Cinematic Universe. It was the first comic book movie in a long time to integrate the fantastical nature of superheroes and supervillains into a real world setting with consequences. It also showed how great of a filmmaker Jon Favreau is and rebooted the career of Robert Downey Jr. For all this, Iron Man is a fantastic movie, still one of the best MCU films. It's so much fun to watch. Yet it displays a lot of intelligence, exploring the internal dilemma of a man profiteering off war when faced with the harsh reality that he is part of a system that corrupts absolutely.