It’s nothing short of incredible that the Marvel Cinematic Universe has never been stronger, the franchise is heading into their highly anticipated Phase 4, and after 20 films Marvel has helped make superhero movies the mainstream. The MCU has been able to turn all sorts of less popular comic book characters into household names, but before all of these tertiary characters were thrust into the spotlight, Marvel was getting all of this started with Iron Man.

Iron Man was far from the most popular superhero upon the movie’s release, but both Favreau’s direction and Robert Downey Jr.’s portrayal of Tony Stark helped turn that around in a major way. Robert Downey Jr.’s Tony Stark had three Iron Man films, but he appeared in a slew of Marvel movies so that the irreplaceable Iron Man could lend his talents where needed. The MCU has come a long way since the first Iron Man, but the mark that the films have made cannot be overlooked.

15 Robert Downey Jr.'s Troubled Past Was An Asset In Jon Favreau's Eyes

Via ComicBook.com

Many people would agree that one of the reasons that the Iron Man movies have been such a success is because Robert Downey Jr. makes for such perfect casting as Tony Stark. Part of this has to do with the fact that Robert Downey Jr.'s own life has several parallels to Stark's own troubled history. Favreau intentionally wanted Robert Downey Jr. to pull from this experience and help it give his portrayal more dimension.

14 The First Iron Man Actually Foreshadows The Mandarin

Via HollywoodReporter.com

The Mandarin is one of the most famous villains from out of Iron Man's roster and while the third film in the series eventually turns to him (kind of), there was talk of using him in the first film, as well. While Iron Man goes a different route, it does include one of the Mandarin's calling cards. Raza wears one of the same rings that the Mandarin will later wear in Iron Man 3, which neatly ties them together.

13 Extras Were Lied To About An Iconic Scene From The First Film

Via SyFy.com

A huge surprise in the first Iron Man is that the movie concludes with Stark blowing his secret identity and announcing to the world that he's Iron Man. It's a powerful moment, but it's one that involves tons of extras to properly pull off. As a way to keep this ending a secret and not get leaked out by any of these many extras, they were told that it was a dream sequence and it was treated as such during filming.

12 Iron Man Puts Real Paparazzi Photos Into The Film

Via People.com

If there's any personality within the Marvel Cinematic Universe that's subject to public obsession and the rampant paparazzi, it'd be Tony Stark. During the production of the first film, some paparazzi were able to leak out some early photos of the suit from the film. In a very clever move, that photo is actually used as the front page image on the newspaper in a story about Iron Man's secret identity.

11 Agent Coulson Was Originally Not An Important Character

Via DigitalSpy.com

Agent Coulson has arguably become one of the most important characters in all of the MCU. He's bridged together the film and television quadrants of the universe and he's still appearing in films, despite his character's death. Originally, the character was just referred to as "Agent" in the script. It's because Clark Gregg had such infectious chemistry with the cast that Favreau began to expand his role and give him a name. The rest is history.

10 Sam Rockwell Was Favreau's Backup Plan If Robert Downey Jr. Wasn't Interested

Via IMDB.com

Many people see Robert Downey Jr. as synonymous with Tony Stark, but during the film's troubled production history, other studios had Tom Cruise and Nicolas Cage under consideration. Marvel also thought about Patrick Dempsey and Colin Farrell, but Favreau and Kevin Feige both always fought for Robert Downey Jr. Favreau’s second choice was Sam Rockwell, who he was at least able to put in Iron Man 2.

9 Iron Man Is The Legendary Stan Winston's Final Film

Via YouTube.com (TopMovieClips)

Stan Winston is a special effects wizard that's more famously known for his designs from horror and science fiction, like the Xenomorph or Pumpkinhead, but he also contributed to the construction of Tony Stark's trio of Iron Man armors from the first movie. Stan Winston Studios worked on building the suits, while Adi Granov designed them.

Related: MCU: Every Iron Man Fight From Worst To Best, Officially Ranked

8 Favreau Almost Tackled Captain America First

Via BusinessInsider.com

Favreau and Robert Downey Jr.'s Iron Man is the movie that kicks off the Marvel Cinematic Universe, but before this ambitious plan was in place, Favreau was considering directing a Captain America movie and Nick Cassavetes was lined up to do Iron Man. Favreau ultimately decided he was more into Iron Man's tone and sensibilities and immediately had Robert Downey Jr. in mind for the part.

7 Iron Man Started Shooting Without A Finished Script

Via VanityFair.com

Now it almost seems impossible that a huge MCU film would go into production without a finished script, but it was a very different time with Iron Man. Even though Robert Downey Jr. and Jon Favreau knew the film's arc and the many action set pieces, the dialogue wasn't locked down. As a result, Robert Downey Jr. got to improvise a lot of his dialogue, which helps add to his incredibly naturalistic performance. It just works.

6 Paul Bettany's Involvement As JARVIS Was An Afterthought

Via TonsOfFacts.com

Paul Bettany has gone on to become an important pillar of the MCU with his role as Vision, which makes his tangential involvement to the series all the more fascinating. Favreau wanted to avoid Batman comparisons by turning Stark's butler Jarvis into an artificial intelligence system instead. Favreau needed a voice for the system, so he called in a favor from his Wimbledon co-star, Paul Bettany. It was barely any work for Bettany and he had no idea how much his presence in the MCU would expand.

Related: MCU: 20 Wild Revelations About Iron Man And Thanos' Rivalry

5 Robert Downey Jr. Gave His Friends Job Opportunities On The Films

Via Amazon.com

Just like how Iron Man was a major opportunity for Robert Downey Jr., he decided to pay it forward when it came to some of the major creative positions for the Iron Man sequels. For Iron Man 2, Robert Downey Jr. pulled some strings so his friend Justin Theroux could write the movie after being impressed with his work on Tropic Thunder. Then, RDJ was instrumental in getting Shane Black to direct Iron Man 3 after their time together on Kiss Kiss, Bang Bang.

4 Robert Downey Jr. Did His Screen Test In A Tuxedo

Via YouTube.com (TopMovieClips)

Typically actors of Robert Downey Jr.'s level don't have to do obligatory screen tests, however, RDJ was coming off of a rough patch and the studio had to prove he was insurable. Downey Jr. went above and beyond and not only did the screen test, but performed it in a tuxedo, which was an incredibly Tony Stark-like move and helped him secure the part.

Related: 15 Reasons Why Robert Downey Jr. Is Actually Tony Stark

3 Iron Man's Rights Passed Through Many Studios Before Marvel Took Charge

Via TheAceBlackBlog.com

Marvel Studios would eventually be the ones to get the MCU started with Iron Man, but back in 1990 Universal Pictures owned the rights to the property and were trying to make a movie happen. From Universal, the rights moved onto 20th Century Fox and then New Line Cinema. After decades were wasted with no progress, Marvel took charge themselves.

2 Kids And Toy Sales Helped Make The Film Happen

Via PopSugar.com

When Marvel Studios decided that they'd be producing an Iron Man film themselves, one of their main priorities was to sell toys just as much as it was to generate a high box office title. In addition to the relevancy of toys, Marvel also held a focus group with children to see which of their characters they were more interested in and it turns out that they favored Iron Man.

1 The Iron Man Films Have Almost Made As Much As Tony Stark Himself

Via Money.com

Collectively, the three films in the Iron Man franchise have made over two billion dollars. Now a billion dollars per MCU film is almost the standard, but the Iron Man movies were the first of the lot and still made bank when the genre was far from a proven success. They've brought in a staggering amount that would even make Tony Stark jealous.

Next: 20 Greatest Non-MCU Robert Downey Jr. Films, According To Rotten Tomatoes