With Hollywood studios hurrying to get as many superhero blockbusters as possible into production, everyone is looking for the next sure thing - and fans are casting doubt on some before they're even off the ground. But the truth is, sometimes the stories least likely to succeed turn out to be the biggest hits.

Here are Screen Rant's 10 Great Superhero Movies That Surprised Everyone.

Batman

Best Batman Actors Michael Keaton

In the 1990s, the most famous version of Batman outside of the comic books was the campy Adam West TV show. So a big screen version of the hero was going to try something different. A little too different for most fans. So when Tim Burton landed the job as director, the man behind Pee Wee's Big Adventure seemed like a guaranteed flop - especially when he cast the comic actor Michael Keaton as Batman. Everyone knows those fans were 100% wrong: not only was the movie a blockbuster hit, but it paved the way for darker superhero stories in general. And Keaton surprised critics even more, becoming the quintessential Batman for entire generations.

X-Men

X-Men

Back in the year 2000, the idea of superheroes, or even a superhero team dominating the blockbuster market was unheard of - let alone a team of mutated outcasts in black leather. But director Bryan Singer didn't see the X-Men as heroes, or a potential shared universe franchise: just a cool story. Imagining the battle for mutant freedom as an allegory for the Civil Rights movement - with Magneto and Professor X filling in for Martin Luther King, Jr. and Malcolm X - the movie was a hit. It kicked off a series, and the superhero genre as a whole, while making more than a few overnight superstars along the way.

Spider-Man

10 Superpowers You Didn't Know Spider-Man Had

Adapting a team of mutants into a popcorn thriller is one thing, but adapting a hero as iconic and effects-heavy as Spider-Man? The job seemed impossible, especially with the supremely un-hunky or musclebound Tobey Maguire in the lead role. But the studio and director Sam Raimi didn't back down from the challenge, showing that big screen superheroics on the level that fans imagined were finally possible, while setting the mold for almost every superhero origin movie to follow. The Spider-Man film franchise has ran into trouble since its hit debut, but starting with such a massive success wasn't predicted by anyone.

Batman Begins

Batman confronts Jonathan Crane in Batman Begins

After Joel Schumacher's neon, nippled Batsuits basically killed the Batman movie series, there were some who thought it would take a decade for the sting to wear off. Instead, Warner Bros. moved on with a new spin from director Christopher Nolan. The cerebral, brooding director seemed to be just as strange a choice as Burton had been, and his pick of an unknown Welsh actor for the lead role doomed the project for a lot of fans. They were left eating their words, as Batman Begins - and Christian Bale - delivered a wildly successful version of the Dark Knight for a brand new generation. Not to mention setting the stage for one of the best comic book films - and versions of Batman's famous enemy, the Joker - that may ever be made.

Superman

Christopher Reeve is Superman

The tagline of this 1978 movie says it all: "You'll Believe a Man Can Fly." Back then, that promise alone was enough to convince movie fans they were in for a revolution in movie-making. It's hard to imagine there ever being a time when a Superman movie seemed impossible, especially one that actually featured polished versions of his superpowers. But the movie delivered on the promise, and then some. The biggest surprise was the star, Christopher Reeve. The grinning unknown actor may have been the only person capable of pulling off the role, proving to be as much of a hero off-screen as he was while cameras rolled. Forget a surprise: for its place and time, Superman was, and is, one of the best superhero films ever made.

Iron Man

Robert Downey Jr - Facts You Didn't Know Iron Man

Sure, Tony Stark is a box office veteran these days (and the same goes for the insanely successful actor who plays him). But when Marvel first tried to bring its B-level superhero to the big screen, it was hard to understand why. A millionaire in a suit of armor with shrapnel in his chest seemed like the worst hero to build a movie around, and casting Robert Downey, Jr - best known for his drug problems - seemed to condemn the entire project. Fans know how this one played out, with Downey, Stark, and director Jon Favreau turning in what still might be Marvel's best movie. It's a good thing, too - the entire Marvel Universe was riding on Iron Man being a hit.

The Avengers

Marvel's The Avengers

Marvel fans saw their wildest dreams made real when the movie versions of Iron Man, Thor, Captain America and Hulk were all building towards one massive ensemble adventure, but it's easy to forget that at the time, nobody knew how the idea would actually play out (since solo heroes sharing the screen after their own introductions was unheard of). Would there be enough time for each hero to shine? Could a threat arrive that actually tested their combined talents? And could writer and director Joss Whedon successfully manage a blockbuster with so much riding on it? The answer was yes, across the board. The Avengers delivered on every hope, locking Marvel's movie universe in place, and putting Whedon in charge of guiding every one of their sequels.

Guardians of the Galaxy

Guardians of the Galaxy full team

Even with Marvel's Avengers a worldwide hit, and even with the studio's bet on underdog Joss Whedon paying off and then some, the announcement that Guardians of the Galaxy was actually going to be made (with a blockbuster budget, no less) seemed too weird to be true. Cap, Thor, and Iron Man, sure, but making a team of green-skinned aliens, a talking raccoon and walking tree work? With director James Gunn in charge, the movie would be unforgettable, but probably not a mainstream hit. Defying even the highest hopes, Guardians wound up having one of Marvel's biggest box office runs ever, proving even the weirdest stories can be a billion-dollar property, if they're told the right way.

Captain America: The Winter Soldier

Chris Evans and Scarlett Johansson as Black Widow in Captain America: The Winter Soldier

The biggest question mark of Marvel's Phase 2 was Captain America's first solo movie set in the modern era. He helped launch The Avengers, but needed a brand new story to make a solo series worthwhile. He got one in The Winter Soldier, with the massive reveal that SHIELD had been infiltrated by the enemy of his first movie, eventually bringing the agency down, and spinning the TV show based in its universe on a new path. Most surprising were the directors, whose experience on shows like Community and Arrested Development seemed a bad fit for superheroes. That was dead wrong: The Winter Soldier was one of the slickest action movies Marvel ever made, with the Russos - and Cap - in the driver's seat for Marvel's Phase 3.

Deadpool

Deadpool sets R-Rated comic book movie record

Some comic books are especially hard to adapt - so complicated or fantastic are their characters or fiction, that developing a movie script is deemed nearly impossible. That wasn't the case with Deadpool, though: the Merc with a Mouth's movie was put into development hell by some Fox executives alone. After years of re-writes, a PG-13 version of the story being crafted to appease the higher-ups, and with a budget of less than $60 million, star Ryan Reynolds blew the doors off the box office, beating some of Marvel's heaviest hitters and becoming one of the highest-grossing R-Rated movies EVER. Since Deadpool could have proven skeptics wrong with just a fraction of that success, it takes the cake.

Conclusion

Those are the superhero movies that people doubted the most, eventually turning out to beat the odds, and create entire franchises in the process. Which superhero movies most surprised you, for better or worse? Let us know in the comments, and remember to subscribe to our channel for more videos like this one.