Robert Downey, Jr. is so closely associated with the character of Tony Stark that it's hard to imagine anyone else assuming the role. (And it's true -- he probably can't think of anything else either; the last time he played a character who wasn't a genius billionaire playboy philanthropist was way back in 2014.)

But it wasn't always like this. For a time, one of the biggest stars on earth was being eyed for the roll. And it would have been a very different Tony Stark indeed.

The history of the "Iron Man" film takes more twists and turns than the actual movie does, but it began in 1990, with Universal quietly developing the property as a vehicle for writer-director Stuart Gordon. (His take was going to be grungy and low budget and, judging by his previous output, very funny.)

From then on, the project went through at least two more studios (20th Century Fox and New Line), before finally returning to Marvel and the then-burgeoning Marvel Studios (under the supervision of producer Kevin Feige).

In the late 1990's, while the movie was still being tinkered with at Fox, Tom Cruise expressed an interest in playing the arms-dealer-cum-superhero. But, at the time, so many names were being tossed around (including, of course, comic book super fan Nicolas Cage), that it's hard to figure out what was just rumor mongering and what had some basis in fact. But Feige actually addressed the casting rumor in 2004, shortly after New Line gave up on developing the film and passed the right back to Marvel Studios. (New Line had attempted a number of versions of the movie -- including one that would have potentially been written and directed by Joss Whedon.) The typically political Feige said, "There have been discussions [with Cruise] over the past several years and there are a number of factors involved."

Many of those factors were, undoubtedly, money-related.

When production began on "Iron Man," Marvel Studios was just starting out. The idea of an independent production company born out of a comic book company seemed crazy. And, to some degree, it was.

But under the visionary leadership of Feige, it was also brilliant, and shaped much of the cinematic landscape for the following ten years. But in those early days, they didn't have either the creative or financial capital to throw around. They had to be smart and lean and scrappy.

While it seems like there were some discussions, in earnest, for Cruise to be the first hero of the nascent Marvel Cinematic Universe, the heard reality was that they probably couldn't afford him.

They could, however, afford Robert Downey, Jr. When RDJ was hired for the role, he was shaking off the reputation for being a troubled performer; an actor who got more attention for his run-ins with the law than the movies that he was starring in. At the time, he was an unknown commodity and a potentially risky one at that. Just a couple years earlier, he had to drop out of a Woody Allen film because the insurance company wouldn't cover him. He was a brilliant actor but an unpredictable one. And, again, the visionary, risk-taking Feige listened to his creative team (led by director Jon Favreau) and made the call: Downey, Jr. would be Iron Man.

He'd go on to essay the character through some of the most successful movies of all time, including this past weekend's "Avengers: Infinity War," which is already breaking box office records both at home and abroad.

In the years since "Iron Man's" release (and subsequent runaway success), Cruise has downplayed his involvement in those early discussions and dismissed his interest in the genre as a whole.

In 2016, when Jimmy Kimmel asked if he had ever been approached to be in a superhero movie, Cruise flatly said, "No." "I enjoy those films a lot," Cruise said. But his commitment to the "Mission: Impossible" (and, at the time, "Jack Reacher") franchises meant that he was more locked into "different kinds of films."

And just this past week, while talking up this summer's "Mission: Impossible – Fallout" at CinemaCon, he was asked how close he came to assuming the shiny robotic armor. "Not close," Cruise told "I love Robert Downey Jr. I can't imagine anyone else in that role, and I think it's perfect for him." He did seem to walk back his earlier commits about not being interested in those types of movies. "I look at a movie and I don't rule anything out," Cruise said, somewhat optimistically.

So that leaves us just a little bit hopeful -- just because he wasn't Iron Man, doesn't me he can't bring another four-color hero to life on the big screen. This is Cruise after all; he can do just about anything.