Marvel Comics' passionate fanbase often creates high expectations for the actors who bring beloved comic characters to life, especially for the first time. Thankfully, the vast majority of actors have honored the heroes and villains they portray with standout debut performances. These portrayals embody much of what made the characters so engaging in the source material.
Robert Downey Jr. is undeniably remembered as the face of the MCU, even after Tony Stark died in Avengers: Endgame. It is hard to imagine that when he first appeared in the role in 2008's Iron Man, the idea of launching a franchise was barely on fans' radar.
Downey Jr. exceeded expectations in the titular role, especially because Tony Stark was one of the less popular characters in Marvel Comics. He managed to make Tony Stark immensely important and beloved, which helped to launch the MCU as a franchise and provide a career restart for himself.