Here's how 'Iron Man' built the modern Marvel Cinematic Universe in 5 phases

In the summer of 2008, Iron Man made Marvel Studios believe that the idea of an interconnected cinematic universe could fly. Fifteen years and five phases (and counting) later, the nascent company's big bet on an unfamiliar hero, an untested director and an unlikely star has reaped rewards many times over. Although it wasn't the biggest comic book-based hit of 2008 — that honor goes to Christopher Nolan's The Dark Knight — Iron Man finished a strong second in terms of domestic box-office grosses and first in the hearts of audiences hungry for new costumed avengers as opposed to variations on previously adapted characters.

"Iron Man is a paradigm example of risk rewarded," Ben Saunders, Director of the Comics Studies Minor at the University of Oregon, tells Yahoo Entertainment. "Everyone involved took a bit of a gamble — and boy, did it pay off."

That Marvel's gamble worked is even more impressive when you peer under the hood of Iron Man and realize how much trial and error, not to mention good old-fashioned luck, followed the movie right up until it premiered in theaters on May 2, 2008. With no real infrastructure in place, producer Kevin Feige and director Jon Favreau were inventing and re-inventing the production on the fly, throwing out whole storylines, experimenting with effects and allowing improvisation to craft many of the scenes that would ultimately make the movie soar.

On a DVD bonus feature, Favreau compared the process to making a "small indie art film" in superhero clothing, and author Tara Bennett says that served as the model for many of the Marvel films that came after, up to and including James Gunn's Guardians of the Galaxy trilogy, which concludes with the just-released Vol. 3. "They were kind of fumbling their way forward as a studio," notes Bennett, who spent four years inside the Marvel machine with Paul Terry to co-author the 2021 bestseller The Story of Marvel Studios: The Making of the Marvel Cinematic Universe. "Not in terms of not knowing what they were doing, but just trusting their gut. Every step was a proof concept and Iron Man was their North Star."

To mark 15 years since Robert Downey Jr. headed into his lab as entitled warmonger Tony Stark and emerged for his maiden flight as the invincible Iron Man, we're recapping the five phases of the film that laid the cornerstone for the Marvel Cinematic Universe. Call it the "Anniversary Initiative."

Phase 1: Holding out for a hero

Why did Marvel Studios bet the house on Iron Man as their inaugural hero? Easy answer: "It wasn't so much that he was the right choice, but that he was the only choice," says Saunders. Thanks to previous movie licensing deals approved by Marvel Comics, the publisher's most popular characters — including Spider-Man, the X-Men and the Incredible Hulk — were all tied up with rival studios. That left Marvel's still-young film arm, which had been founded in 1996, with a bevy of B-tier characters like Captain America, Thor and Black Widow to headline its first self-financed production as part of a multi-picture distribution deal with Paramount.

Of course, all of these heroes are now household names, but in 2008 they came with additional hurdles for a studio on a limited budget. "Captain America was risky because you'd have to create a period piece, and Thor would have been expensive in order to create a persuasive vision of Asgard," Saunders explains. "So Iron Man became the choice by default, because he was based in our world meaning that no expensive alternate environments needed to be created. He's also a technologically-enhanced millionaire, so the threshold of disbelief is fairly low. We already live in a world of miraculous gadgets so it's not as big a leap as accepting the reality of a Norse God."

For the record, Marvel Studios wasn't the first company to think that an Iron Man movie could be a hit. Created in 1963 by a team of Marvel Comics mainstays, the character's film rights had already changed hands many times — from Universal in 1990 to 20th Century Fox in 1996 to New Line Cinemas in 1999 — by the time he flew back into the Marvel vault. Along the way, he had attracted the attention of such established stars as Nicolas Cage and Tom Cruise, who stuck with the project for years as it cycled through such potential directors as Quentin Tarantino and Joss Whedon. And if you have a hard time seeing Pete "Maverick" Mitchell as Tony Stark, you're not alone.

"There's no doubt that they were better off [without Tom Cruise]," says Syracuse University professor and pop culture expert Kendall Phillips. "Tom Cruise would have brought too much star status to the role. Whatever movie he's in — whether it's Minority Report or Mission: Impossible — it's Tom Cruise. And we had to care about Tony Stark."

"Everybody knows that Tom can do the larger-than-life kind of part that the role required," adds Bennett. "But if you put Tom's face in the suit, there's more of a Maverick kind of feel to it. There's also the chemistry-tempering with the other characters that helps make Tony who Tony is. And would Tom have had the same kind of rapport with his co-stars?"

Cruise was long gone by the time Favreau started seeing actors to play his version of Tony, and Bennett says that the filmmaker ultimately made a choice between two starkly different performers: Timothy Olyphant and Robert Downey Jr. (Appearing on Conan O'Brien's TBS talk show in 2015, the Justified star confirmed that he and Downey auditioned for the film on the same day.)

"Robert had a softer and more comedic element to him, plus there's that self-esteem mixed with vulnerability that he puts into Tony," she says of the two finalists for the role. "If Timothy had done it, it probably would have had a more laconic feel that would have taken some of the edge off of the character's uncertainty. I think all three of them — Tom, Timothy and Robert — would have done something really interesting with the character. But you can't imagine anyone other than Robert now; he's so important to the role."

At the time, Downey's widely publicized substance abuse troubles and career setbacks led to raised eyebrows — including among Marvel execs — about his viability as a leading man. But all that personal baggage actually worked in Tony Stark's favor. "His willingness to play Tony as a work in progress — flawed and impulsive, and capable of being self-regarding even after resolving to do better — is a huge part of what makes his version of Iron Man someone with whom we can identity," says Saunders. "In fact, his Tony Stark is surely one of the most consequential cinematic performances of the early 21st century. No hyberbole: Marvel Studios changed the logic [of comic book movies], and I'm not sure any of that would have happened without him as Iron Man."

Phase 2: Some assembly required

Iron Man went before cameras in March 2007 for a 74-day shoot that started with the opening sequence of the film — Tony's capture in Afghanistan by the Ten Rings terrorist group and eventual escape in the bulky first version of his soon-to-be-iconic armor. While that's the origin of his transformation from profiteer to do-gooder, it's arguably not the true birth of Iron Man. That moment is saved for midway through the film when Tony heads to his lab and assembles the flight-enabled Mark II suit through a series of breakthroughs and mishaps that builds to a glorious lift-off.

In behind the scenes footage included on the Iron Man DVD, Favreau seems keenly aware that the Mark II sequence is the movie's make-or-break moment, comparing it to Tobey Maguire's early attempts to spin webs in Sam Raimi's inaugural Spider-Man outing. Going back even further, it's also comparable to the helicopter rescue in Richard Donner's Superman: The Movie where Christopher Reeve really makes you believe he's leaping a tall building in a single bound.

As far as Paul Terry is concerned, that's a big mission accomplished. "When I saw Iron Man, I genuinely believed that was Robert Downey Jr. doing that test flight," the Making of Marvel Studios co-author says. "Any sort of superhero film that's saying to the audience, 'This human being is going to be flying,' you have to absolutely nail that. But what I also love about that scene is that it's establishing the fantastical element of a guy in an amazingly high-tech suit, while still keeping it grounded. You have to believe what you're watching."

Phillips says the Mark II sequence was also one of the earliest signs that Marvel Studios would be following the Marvel Comics playbook of allowing its superheroes to be super-fallible. "These are heroes who can fail and who can mess up," he observes. "My favorite moment in that sequence is when Tony ends up falling on a car after flying and the alarm is going off and everything's in chaos. It's like, 'Oh, maybe he's not such a genius after all.'"

"I've always thought that the biggest contrast between Marvel and DC is that DC heroes are gods," Phillips continues. "There's no way that Superman can have foibles — he's not gonna mess up, because he's always Superman. The Marvel heroes are much more flawed, whether it's Peter Parker juggling his classes or Tony Stark trying to manage his business. That's what connects us as the audience to them: Even if these heroes aren't entirely like us, they are flawed like us."

For the record, Bennett points to a no-flights, no-iron tights scene that she thinks is just as crucial to Iron Man's success: an extended sequence where Pepper Potts (Gwnyeth Paltrow) literally makes Tony's heart stop while doing some impromptu upgrades on his circulatory system. Speaking of impromptu, that scene was almost entirely improvised by Paltrow and Downey, and that contributes to the charged emotions between the pair, who go on to embody #CoupleGoals for the MCU.

"You're watching the two of them just riff with each other, and creating these little moments of gold," Bennett says. "While writing the book, Jon reiterated to us that they needed to show the vulnerability between Pepper and Tony and that scene just executed it perfectly."

"It's a real important thing," Bennett emphasizes. "There's so much bravado to Tony, so Jon had to establish in the first movie that there was this magical chemistry between Pepper and Tony that gave us another look at who he was. Pepper dials into the humanity of him and makes him someone that you want to watch. Pepper cares about Tony so we care about Tony. We want him to be OK, too."

Phase 3: Courting the fans... and creating new ones

These days, Marvel Studios presentations are the toast of San Diego's world-famous Comic-Con International, with one star after another trotting out to the cheers of the crowd. Marvel's trip to Comic-Con in 2007 — weeks after Iron Man wrapped principal photography, but well before the effects were finished — was a considerably smaller affair. Favreau and Feige were in attendance, along with Downey, Paltrow and Terrence Howard, who briefly played Tony's pal James "War Machine" Rhodes before a salary dispute concluded with him being replaced by Don Cheadle going forward.

Bennett was in the audience for that presentation, and remembers the audience being split between those who knew the characters and those — like herself — who were thinking, "What is an Iron Man?" And the filmmakers notably tried to play to both crowds, with Favreau emphasizing the movie's live-wire comic energy, while Feige teased potential connections to other Marvel characters. "They did a really good job cold-launching the movie," she recalls now. "Walking out, I talked to friends of mine who were longtime Marvel Comics readers and then just general pop culture fans. They teased just enough to make us all go, 'Let me go see that movie.'"

Away from the bright lights of Comic-Con, Paramount and Marvel focused the bulk of their energy on appealing to the "What is an Iron Man?" crowd. The film's trailers and marketing materials gave no hint that audiences were signing up for an entire cinematic universe — just a story about a quick-witted billionaire inventor and his tricked-out suit. But not, you know, that Bat-suited billionaire that moviegoers were more familiar with. "Audiences had seen that there was a dark Chris Nolan Batman movie coming out, and this was the brighter, shinier version," Phillips says of Marvel's initial pitch.

In fact, Favreau had tidied up the movie's narrative to make it even easier for non-Marvel Zombies to hop aboard. Originally, Iron Man was supposed to feature two villains — Tony's right-hand man at Stark Industries, Obadiah Stain (Jeff Bridges), and the Mandarin, who longtime Marvel Comics readers would recognize as a frequent arch-nemesis on the level of the Joker or Lex Luthor.

Prior to production, though, Favreau decided to focus solely on Obadiah's transformation into the Iron Monger, and the Mandarin's introduction was scrapped entirely, although a few Easter eggs remain in the finished film that hint at his presence. (Ben Kingsley's impostor Mandarin made his bow in Iron Man 3, followed by the genuine article — played by Tony Leung — in Shang-Chi and the Legend of the Ten Rings.)

For a former Iron Man newbie like Bennett, that's a prime example of why it's smart for comic book movies to sometimes dodge the fan-service bullet. "Including the Mandarin would have serviced the comic book lovers, but they had to go way beyond that to get the experiment of Marvel Studios to work. Now, we've got all this mythology stitched together in our heads, but at that point there was nothing to stitch together! And the Mandarin ended up being used in a much smarter way down the line, so it was a smart call to pull back instead of going 'We need this to be bigger.'"

"It also allowed Iron Man to offer this really interesting and simple look at oppositional characters," adds Terry. "Tony discovers this nefarious secret in his business that he didn't know about and that builds to the Iron Man vs. Iron Monger battle. That's your story, and your human drama. If you don't have great human drama, then what do you have for audiences? You just have characters with different power sets blasting things."

Phase 4: Save the best for last

Once upon a time, moviegoers headed for the exits as soon as the "Directed by" credit hit the screen. But Iron Man trained audiences to stick around until the "Special Thanks" have scrolled by, not just for Marvel movies, but any major blockbuster with cinematic universe ambitions. On Feige's initiative, that's where Favreau buried his movie's one major bit of fan service: a brief cameo by Samuel L. Jackson as Marvel Comics mainstay Nick Fury, who informs Tony — and everyone in the theater — that they're about to enter a "bigger universe" via the yet-to-be explained "Avengers Initiative."

"At the 2007 Comic-Con, people asked, 'Is it all connected?' and Kevin said, 'Yes,'" Bennett says of how that pivotal moment came together. "That scene was his promise fulfilled. The attitude in those early days was, 'Let's just take a swing and if we fail, we fail, but it gives us a lot of runway if we're successful.' Jon didn't 100 percent understand it, but as a group they decided, 'Let's do it.'"

And Saunders points out that Feige had a back-up plan in case Iron Man failed to launch at the 2008 box office. Later that summer, Marvel Studios would be releasing The Incredible Hulk through Universal, which had unsuccessfully tried to launch a Hulk franchise five years earlier on the backs of Eric Bana and Ang Lee. But the character had a larger pop culture profile than Tony Stark thanks to the vintage '70s TV series and his presence in multiple Marvel animated series.

"The Hulk looked like the safer bet from a brand recognition point of view," Saunders explains. "For Iron Man, there was no equivalent and it was smart of the Marvel Studios not to put all their eggs in one basket even if we now regard the Iron Man movie more highly than The Incredible Hulk."

Like Iron Man, The Incredible Hulk concluded with a Feige-approved post-credits scene that featured Downey in Tony Stark mode teasing the ongoing formation of Fury's super-team, who would officially assemble four years and three movies later in The Avengers. "You have Tony confirming to the fans that these two movies are connected," Terry says. "It was an additional risk to do that. If they don't do that, Iron Man feels like a closed-off story."

"And it still wasn't guaranteed!" he adds. "In a different version of reality, it may not have led to The Avengers. It may not have been possible to do any of those later films. They're hinting at something that's unresolved, telling you that there's a whole other chapter coming over the horizon. And the world clearly went, 'We want to see the next chapter.'"

Phase 5: Do we need an Iron Man?

Tony Stark's solo adventures ended with 2013's Iron Man 3, and that trilogy-capper paved the way for Downey's exit from the universe he helped launch. But Marvel Studios couldn't completely turn away from their North Star, even while populating the MCU with new terrestrial and intergalactic heroes, from Star-Lord and Thor to Black Panther and Spider-Man.

As the company constructed the "Infinity Saga" across three phases of films, Tony Stark served as the story's dramatic linchpin, to the point where the climax of Avengers: Endgame explicitly calls back the last scene of Iron Man. Staring Thanos — and death — in the face, Tony repeats the 2008's movie's final line: "I am Iron Man."

"That arc of Tony going from self-centered narcissist to a person willing to sacrifice himself because it's the right thing to do is the hero's arc that holds up Book 1 of the Marvel Cinematic Universe," Phillips says of those bookended moments. "That's why audiences cared and shed tears in the movie theater — they had seen the character go that far."

With the book closed on Tony Stark, the big question facing the next phase(s) of the MCU is whether an existing or new hero needs to step up and serve as the central spoke that the next years-spanning tale — which Feige has already labeled the "Multiverse Saga" — can revolve around. Phillips, for one, thinks that the recent creative and commercial disappointment of Ant-Man and the Wasp: Quantumania points to these sagas needing to lean on characters that audiences are fully invested in.

"We're with Scott Lang and then within 10 minutes we're launched into this roller-coaster adventure, and I don't know if we've built up enough love for Scott Lang to care," he notes, adding that Brie Larson's Captain Marvel is the most logical candidate to take over Iron Man's place. "I think Brie Larson is great in that role, but Captain Marvel also has the Superman problem at this point in that she's so overwhelmingly powerful. She's not going to get up after a beating and say, 'I can do this all day,' like Captain America did. So far, I'm not seeing that character who's going to carry the heart of the MCU."

Saunders, on the other hand, says he's reaping lots of rewards out of the MCU's more fractured post-Endgame landscape. "WandaVision was an utterly brilliant allegory about how we process grief; I loved the plot twist in Eternals; the Black Widow movie was at least as good as any James Bond movie that I've seen; and the last Doctor Strange movie was superb and visually stunning," he says. "I know there’s a loud minority who love to complain, but I don’t think that the quality of work produced by Marvel Studios has declined at all. If anything, it’s better — more consistent, and with fewer errors."

Now that they're no longer embedded within Marvel, Bennett and Terry obviously aren't privy to whether the studio does indeed have another Iron Man waiting in the wings. But as audience members, the last thing they'd want is for the MCU to tell the same story again. "If they decided to pick a character to build Phase 4 and 5 around, we'd all just say, 'You already did that with Tony,'" Bennett says. "There's something to be said for them not wanting to repeat Iron Man. They're not just resting on their laurels: This is all about the alchemy about what happens when you try and succeed or don't succeed."

Iron Man is currently streaming on Disney+.