It's no secret that the MCU has been a cultural juggernaut since its inception in 2008 (even if its influence seems to be on the wane amid a touch of superhero fatigue), and the de facto face of the cinematic universe has always been Robert Downey Jr.'s Iron Man.
It shouldn't come as a huge shock, then, that Christopher Nolan – who himself made some genre defining superhero flicks with the Dark Knight trilogy – thinks Downey Jr.'s Iron Man is one of cinema's key casting decisions.
