Like many longtime fans of Iron Man, I couldn't picture a scenario in which actor Robert Downey Jr. could possibly do justice to the role -- until I actually saw the film.

For sure, Downey as Tony Stark, the billionaire industrialist who occupies Iron Man's armor, doesn't have the Errol Flynn-like elan that artists Don Heck, Steve Ditko and Gene Colan brought to the character in the early 1960s. By that criterion, only George Clooney, who has avoided superhero movies like the plague after the colossally silly "Batman & Robin" tanked, has the right look for the role.

For comic book purists, Downey's Tony Stark also lacks the tragic gravitas of David Michelinie and Bob Layton's drunken imperialist. Still, there are moments of emotional vulnerability that shine through in Downey's performance. He doesn't play the weapons manufacturer as some Chaplinesque clown as some -- including me -- feared he might. He's more the optimistic Tony Stark of the early Marvel Age than the conflicted anti-hero of the comic book moment -- and that's a good thing.

Unlike the brooding protagonist of "Extremis," the series that defines Iron Man today, Downey's Tony Stark doesn't store his armor in the marrow of his bones. He's not on the cutting edge of nanotechnology, yet. The Iron Man of Jon Favreau's film is still a creature of circuits and wiring. He has yet to become the Machiavellian figure that will dominate his fellow superheroes in the Civil War series or organize six of the world's most powerful heroes into a shadowy super Politburo that calls itself the Illuminati.

What Downey does so well in the Iron Man movie is capture the essence of the Marvel Comics character as co-creator Stan Lee originally imagined him. While it is fair to say that during the character's 45-year history there have been many iterations of Iron Man, there has been only one Stark.

Under the armor, the secret of Stark's appeal for more than four decades has been his ability to transcend his flaws -- including a damaged heart -- and other insecurities through sheer ingenuity. Other than a mastery of technology, there's nothing extraordinary about Stark. He's a man in a suit of armor, a technology that has been with us since the Middle Ages. Stark has merely modified and upped the game. Anyone with access to technologically enhanced armor can become Iron Man, making him the most democratic of superheroes in a way.

Like the knights who populated the Arthurian legends and the very real soldiers who have died on battlefields throughout all of human history, Stark carries his real human passions into battle with him. Like the men who encased themselves in iron during the medieval era, Stark is pragmatic about staying alive first and becoming a hero second.

Unlike many of his superhero brethren, Stark isn't motivated by a great moral crusade to avenge the murder of either a parent or a loved one, like Batman's Bruce Wayne or Spider-Man's Peter Parker. He doesn't personify a set of universal ideals like Superman or Captain America. He's not the result of scientific folly like the gamma-radiated Hulk or heir of a mystical birthright like the mighty Thor. He did not receive a ring from the space gods like Green Lantern or drink a formula that made him the world's fastest human like the Flash.

Tony Stark became Iron Man to fulfill a real need of the moment. An ordinary man with no superpowers beyond his big brain, Stark built an invincible iron suit to get out of a life-threatening jam. Who can't relate to that?

Over the years, comic book fans have watched in fascination as Stark evolved from dogmatic Cold Warrior to a man who renounced the legitimacy of making weapons of mass destruction for any government. We've watched him wrestle with the contradictions of his skepticism about militarism even as he wields the mightiest armor on the planet and later become the U.S. Secretary of Defense. We watched him form the Avengers, reveal his secret identity to the world, fall into political disgrace and bounce back to take over the world's most sophisticated intelligence agency.

He has turned Stark Industries into an incubator of eco-friendly technology and spent quality time on skid row drowning his sorrows in an alcoholic blur. Unlike the weirdly ascetic Bruce Wayne, Stark happily sleeps with the most beautiful socialites, female super heroes and super villains in comics. He is nothing if not well-rounded.

Through it all, Stark has always managed to embody what it means for an ordinary American man to be in the midst of a perpetual mid-life crisis. He's flawed, immature, petulant, morally reckless and self-aggrandizing. Tony Stark's a playa. Still, he has made his choice to become a hero look natural, if not exactly easy. That's why Robert Downey Jr.'s performance is a masterstroke. He makes us realize that if a scoundrel like Tony Stark can become a hero, there could be hope for the rest of us.