On May 2, 2008, the world of superhero cinema changed forever. Iron Man, Jon Favreau's first foray into genre filmmaking, made its silver screen debut to the tune of over half a billion dollars internationally, and would usher in a new era of flights and tights cinema with the introduction of the groundbreaking "cinematic universe." The film also signaled the rebirth of one of Hollywood's most formidable talents: Robert Downey Jr. While RDJ was a huge risk for the studio's image, he was a natural fit for the role and tone of the film. While the risk eventually paid off for the studio, Downey Jr. was by far not the studio's first choice to don the famous iron suit.

Although it seems like a no brainer in retrospect, the 43-year-old thespian was considered by many to be over the hill, especially for the freshman entry into a potentially multi-picture franchise. But Favreau saw something in Downey Jr's performance; a punch-drunk mix of charisma, comic timing and gravitas that would ultimately win him the job. It sounds strange, then, to think that so many other actors were considered for a part seemingly made for Downey Jr.

CBR has compiled a list of the top five actors who nearly stole the role, five who very well could once RDJ hangs up his iron duds, and five who should don the iron cowl (but probably won't, for a number of reasons).

15 TOM CRUISE (ALMOST CAST)

Some interesting news resurfaced recently that pegged Hollywood icon Tom Cruise as one of the original front runner's for the role of Tony Stark/Iron Man. Speaking in a recent interview, during filming the sixth installment of the Mission: Impossible franchise, Cruise clarified his involvement, stating, "Not close. Not close and I love Robert Downey Jr. I can't imagine anyone else in that role and I think it's perfect for him."

That said, it's not hard to imagine the 56-year-old in the role, playing a man after his own heart. His legendary stunt work alone makes him a shoe-in on paper, and the range of his acting chops across his 35 years in the business puts him right up there with RDJ in the talent department.

14 HUGH JACKMAN (ALMOST CAST)

If there's anyone who knows how to take a role and make it his own, it's Hugh Jackman. Having played Wolverine a record 11 times (counting photo cameos), Jackman has completely redefined the character for generations to come. While Jackman was merely considered to play the part before RDJ, it's not hard to imagine why.

Along with being one of the most physically committed actors of his generation, he is also one of the most talented. From playing the charismatic, obsessed showman in Christopher Nolan's The Prestige (2006), to his cagey and dynamic turn in 2013's Prisoners, Jackman displays a range few of his contemporaries can match. It’s not hard, then, to believe the 6'2" Australian stepping into those iron boots.

13 NICOLAS CAGE (ALMOST CAST)

Nicolas Cage is one of those rare Hollywood talents whose name seems to show up on just about every major franchise movie list in some form or another. There was his rumored involvement as Scarecrow in Joel Schumacher's scrapped third Batman film, his near-miss playing Norman Osborn in Sam Raimi's Spider-Man (2002), and his legendary almost-performance as Superman in Tim Burton's Superman Lives.

The superhero roles that Cage has landed have been just as eccentric and diverse; the fiery stuntman Johnny Blaze in 2007's Ghost Rider, Big Daddy in 2010's Kick Ass, and a handful of voice roles for animated features. While Cage would have been an odd choice to play Iron Man, he came close enough to get a mention on this list.

12 SAM ROCKWELL (ALMOST CAST)

Prior to the casting of Downey, Jr., director Jon Favreau had initially approached Sam Rockwell to audition for the part. At the time, Rockwell had been known for his range and ability to play the bad guy, the best friend, and the back stabber, all while stealing every scene (and knowing it). A veritable chameleon of the silver screen, it's no wonder Favreau could envision Rockwell as his Tony Stark.

Though he lost the role to Downey Jr., he would eventually enter the MCU in 2010's Iron Man 2, portraying Tony Stark knock-off/nemesis, Justin Hammer. Remove Hammer’s goofy glasses, and it’s easy to see Rockwell as the perfect Tony Stark.

11 TIMOTHY OLYPHANT (ALMOST CAST)

Looking at the guy, it’s somewhat of a mystery why Timothy Olyphant hasn't played a superhero yet. He got close in 2007, when he allegedly auditioned for the role of Tony Stark on the same day as Robert Downey Jr.

While the screen test has yet to surface online, Olyphant would have been a solid choice, though his resistance to franchise filmmaking (having turned down Vin Desiel's part in The Fast and The Furious and his unwillingness to star in the sequel to 2007's Hitman) might not have jived for the studio. Though Olyphant was never officially offered the role, one wonders if his desire to pursue darker, lower budgeted fare might have made him an obtuse fit for the sprawling franchise.

10 MILES TELLER (COULD)

Forget the fact that Josh Trank's Fantastic Four (2015) completely crashed and burned with both critics and fans alike. Forget the Divergent franchise and all its foibles. Miles Teller was made for the Hollywood blockbuster.

With the acting chops to go toe-to-toe with the likes of J.K. Simmons, the comedic timing to hold his own against contemporary funnyman Jonah Hill, and the versatility to jump from sports drama (Bleed For This), to PTSD rattled military vet (Thank You For Your Service) to everyman heartthrob (The Spectacular Now) -- he a perfect candidate to don the iron suit. He's also about to enter stratospheric territory starring opposite Tom Cruise in Top Gun 2. Money’s on Teller to be a serious contender come re-casting time.

9 CHRIS PINE (COULD)

Take everything mentioned in the talent department about Miles Tellar, and add pulling off the impossible by re-inventing the role of Captain Kirk, and you've got another top-notch contender. While Pine's familiarity may already be too cemented in the Star Trek and Wonder Woman universes, Pine emerges as a strong candidate when RDJ eventually decides to retire.

He may be older than some on the list, but he's still younger than Downey Jr., and -- depending on which direction Marvel decides to go next with the character -- is the perfect age to play a seasoned-yet-wild child version of Tony Stark. Plus, his comedic timing and charm seem a perfect complement to the salty Tony that RDJ has accustomed fans to.

8 JOSEPH GORDON-LEVITT (COULD)

Back in 2012, Joseph Gordon-Levitt seemed like the inevitable choice for Warner Bros. and DC to take over for Christian Bale as Batman. After all, his character did basically receive the keys to the Batcave at the end of The Dark Knight Rises (complete with a final shot in which he literally rises).

While fate had other plans for the Bat-franchise, audiences got to witness his potential as a superhero. In addition, JGL is one heck of a comedic actor, and has a resume peppered with commercial and critical successes that should comfort any major studio betting it all on him. He's also a comics fan, which puts his take on any character from the Marvel Universe in good hands.

7 ARMIE HAMMER (COULD)

Armie Hammer never auditioned for Iron Man, but he did audition for (and land) the role of Batman. Yes, about a decade ago, Hammer was cast to play The Dark Knight in George Miller's scrapped Justice League Mortal. Since then, his name has been thrown around Hollywood for roles just about every superhero role.

Aside from the physicality, resonant voice and square jaw, the dude can act (take a look at J. Edgar if you need convincing on this front). Plus, he's also the real life heir to a multi-million-dollar fortune. Could the guy be any more Tony Stark? The jury's out on his technological prowess, but if Marvel wants to recast their Iron Man as a younger, more brooding hero, Armie is their man.

6 SCOTT EASTWOOD (COULD)

After years of living in his father’s shadow, it looks like Scott Eastwood is finally coming into his own. This is just one of the many traits he and Tony Stark share in common. They are also both devil-may-care men who easily slip into the role of life of the party. One could even imagine his father Clint playing Howard Stark, in an all too meta Hollywood moment.

And just like Tony, Scott isn't afraid to break from his dad's legacy and forge his own path; in fact, Scott and Clint's acting choices couldn't be more different. He’s also basically auditioned for the role as Iron Man already... with his role in the Pacific Rim sequel requiring him to wear a similar looking metal suit.

5 JEFFREY DEAN MORGAN (SHOULD, BUT WON'T)

Had Jeffrey Dean Morgan been a more prominent name back in 2007, there's little doubt producers would have considered him for an audition. Morgan is an actor who can inhabit dark, brooding, charming characters, while managing to bring levity and his own brand of sardonic humor to the part. Morgan's also had tons of previous comic book film experience; playing Thomas Wayne in Batman v. Superman, Clay in The Losers, The Comedian in Watchmen, and most recently Negan in The Walking Dead.

Unfortunately, the actor is too old to take over a franchise like Iron Man, and might be too closely aligned with his other iconic work to give new life to the character – not to mention too similar in mien to Robert Downey Jr.

4 EZRA MILLER (SHOULD, BUT WON'T)

Besides being a scene stealer in virtually every film he's in, Miller is so close in general mischievousness and wit to a young Tony Stark, it's kind of scary. After proving his can handle his own -- and even outshine -- the likes of Batman, Superman and Aquaman in Justice League, Miller has shown that he has what it takes to carry a superhero film.

Unfortunately, he's already locked in to playing another crimson and gold-colored superhero to even be considered for Iron Man. It's too bad, because Miller could really take the character to new heights, with his age allowing him time to grow and build out Tony's arc outside of the suit, perhaps much more than Downey Jr. was ever able to.

3 GEORGE CLOONEY (SHOULD, BUT WON'T)

If George Clooney was able to get his hands on a time machine, he'd probably dissuade his younger self from ever taking the role of Batman in the much derided Batman & Robin (1997). Yes, while Ben Affleck was busy collecting his Good Will Hunting Oscar and Christian Bale was still earning his stripes in a series of indie flicks, Mr. Clooney was cashing out his career chips by donning a nipple bearing bat-suit and fighting off a very goofy Mr. Freeze.

If Clooney had never been Batman, he'd be a serious contented for an older, more refined Tony Stark. Suave, industrious and enormously talented, Clooney has everything it takes to (theoretically) land the part. Gotta blame the bat-nipples on this missed opportunity.

2 ALDEN EHRENREICH (SHOULD, BUT WON'T)

Similar to Clooney, Alden's career may be forever marred in big budget genre filmmaking by a major casting misstep. While it may not be Alden's fault that Solo: A Star Wars Story fell apart like it did, his intergalactic hero appeal surely went out the window. It's a shame really, considering that Alden's career appeared to be on the rise, with the 29-year-old emerging as one of Hollywood's hottest talents.

Applying the Clooney time machine theory, it is easy to see Ehrenreich eschewing the role of Han Solo, and stepping into the role of billionaire/wildcard/womanizer Tony Stark. He might even bring a sense of youth and naiveté that could help redefine the character as more vulnerable, untested, stoic anti-hero.

1 JON HAMM (SHOULD, BUT WON'T)

Last but not least, Jon Hamm. Aside from the fact that he basically played a version of Tony Stark for the last decade in AMC's critically acclaimed Man Men, he's also been rumored for just about every upcoming major super hero role under the sun. From fighting off the role of Superman with a Kryptonite stick, to flirting with the notion of donning Bruce Wayne's cape and cowl, Hamm emerges as the perfect actor (on paper) for the role.

Sadly, this will probably never happen. For one thing, his age limits how many sequels he can do. Also, his inseparability with the Don Draper persona in the public consciousness is a major hurtle; one that not even Super-Hamm, Bat-Hamm or Iron Hamm could overcome.