Iron Man was one of the first films in a series that no one truly saw being as successful as it is. Going into Iron Man most people assumed that at best it be OK (Die hards clearly had their own expectations). What makes this such an iconic comic book film is: 1) it was one of the first times weve had our hero go against the norm and announce his true identity and 2) A post credit scene which tells us that inevitably a bigger story is coming together. That 2nd statement has become a staple within the franchise that after every entry in the series people wait specifically for that added part to see where the series will take us. Beyond it being the first film in an array of entries into the series, Robert Downey Jr. was born to play Iron Man. For most of Jr.s career hes essentially been Iron Man (minus the suit). Follow that up with a bald Jeff Bridges as the villain there was nowhere to really go wrong. Without the success of this film, the whole series may have not come to fruition.