One of the most important aspects of making a film is casting. Even if the most talented director is calling the shots behind the camera, the stars of the show need to be up to par in order for the movie to leave a real impact with audiences. Filmmakers have to make sure they have the right thespian for every role, so often times several talents are tested for Hollywood's biggest parts.

Because so many actors can be in the running for certain characters, they ones who don't make the cut can almost be as interesting as the ones who do. As we've said before, the movie industry is a place full of fascinating "what ifs," where viewers' favorite flicks could have been greatly altered by just one choice.

Here are Screen Rant's 10 Movie Castings That Could Have Changed Popular Films

Captain America: The First Avenger

By now, everyone knows Chris Evans as the Star Spangled Man. He's put such a stamp on the role that it's almost difficult to see anyone else donning the classic costume. But when Marvel was casting the part, The Office star John Krasinski was in the running for the role. He exemplifies the optimistic and gung-ho attitude that's so vital to the character, but it would have been interesting to see if Krasinski had the action chops to pull off Captain America's amazing feats and turn in a well-rounded performance. He's known mostly for his comedies, so it'd be a definite change of pace.

On the flip side, Evans had already proven himself capable of being a lead in a superhero movie. His turns as Johnny Storm in the maligned Fantastic Four films of the mid-2000s are considered one of their few highlights. Evans had the screen presence to be an Avenger, he just needed a better script to bring the whole thing home. Luckily, The First Avenger had that, and Evans went on to become one of the franchise's poster boys.

Superman

For many people, Christopher Reeve was and always will be Superman. The classically trained actor perfectly embodied the Last Son of Krypton and casts an overwhelming shadow over anyone else who wears that costume. But would the Man of Steel have left such an impact on popular culture if he had been played by none other than the Italian Stallion? Yes, at one point Sylvester Stallone lobbied hard to get the part. However, he was turned down for being "too Italian." But there's a whole other layer to this that makes it one of the most surreal stories in movie history.

For some reason, Marlon Brando (who played Superman's father Jor-El) had casting approval rights. Stallone discovered this and learned that Brando was actually the one who turned him down. Understandably, Stallone held a grudge against the acting legend, criticizing Brando for using Superman as an easy paycheck and not much more. Stallone argued that unlike Brando, he had a true passion for the source material and was a fan of the comics mythology. Rocky had made him one of the biggest stars on the planet, but would he have done Clark Kent justice? We'll sadly never know.

Star Wars: Attack of the Clones

Whether you blame Hayden Christensen's acting ability or George Lucas' porous dialogue, reaction to the second Star Wars prequel was so negative that it ended the young thespian's career before it really got off the ground. And while Christensen will always be haunted by that fact, one of this generation's finest actors had the foresight to politely turn Lucas down and pursue other projects. We speak of none other than Leonardo DiCaprio.

The perennial Oscar snub actually had a meeting with Lucas to discuss the part, which had to be recast due to the large time jump between The Phantom Menace and Attack of the Clones. But he also had his eyes set on Martin Scorsese's Gangs of New York and opted to work on the period crime drama instead. DiCaprio displayed some amazing Jedi abilities, since Gangs launched one of the new millennium's most successful actor/director combinations that's still going strong today. As talented as he is, even DiCaprio may not have been able to convincingly complain about sand.

Jerry Maguire

Tom Cruise played the character of Jerry Maguire so well, that viewers get the impression that he's just playing himself in the sports comedy. It's a role that's so tuned into his strengths as a performer, fans of the film may be surprised to find out that Cruise was not director Cameron Crowe's first pick for the part. Crowe had envisioned Tom Hanks playing Maguire when he was first writing the screenplay, which makes it seem he had an entirely different idea for who the sports agent was during the earliest stages.

When Crowe was ready to enter production, Hanks had become too old for the part, and the Oscar-winner was already working on That Thing You Do! Nobody is denying that Hanks is an all-time great who is deserving of every accolade he receives, but it's so hard to picture him as Maguire when you view the finished product. Cruise's dynamic and boisterous take is seen by some as the high point of his career. Imagining Hanks going toe-to-toe with Rod Tidwell over the phone just seems wrong.

Casino Royale

After 2002's Die Another Day, it was time for a new James Bond. Before the reboot Casino Royale, producers cast a wide net searching for the next 007. As you might know, they selected Daniel Craig. The actor's tenure as Britain's famous spy has been a little different from the more light-hearted outings of the past, but Craig still maintained some of the classic Bond traits that make him recognizable as the secret agent. He has the charm and dry wit that's been with the character since Sean Connery.

Before Craig was chosen, one of the finalists was Sam Worthington, star of James Cameron's Avatar. In his many attempts to become a Hollywood leading man, Worthington has decidedly not shown any of the characteristics that are commonly associated with James Bond. He's often been criticized for being a blank slate that doesn't bring much to the table (and not in an endearing Keanu Reeves way). It's difficult to picture him as the sly and slick 007. At least he still has those Avatar sequels to look forward to.

Toy Story

For an entire generation of moviegoers, Tom Hanks and Tim Allen will forever be intertwined due to their partnership in Pixar's flagship Toy Story franchise. But for a moment, it looked like Hanks would be joined by someone else in Andy's bedroom. The studio originally offered the part of the space ranger to comedian Billy Crystal, but he turned it down. After seeing the film, Crystal considered it one of the biggest mistakes he made in his career. But in retrospect, it all worked out for the best.

Crystal's hyperactive, manic style of delivery may not have been the best fit for the Buzz character, who seemed better suited with Allen's macho aloofness. Especially in the first film, where Lightyear had the bravado of a tough guy, Allen's sensibilities carried the character in a way Crystal may not have been able to. However, Crystal was still able to join the Pixar universe some years later when he voiced Mike Wazowski in Monsters, Inc., a role that seemed tailor made for his talents.

Pulp Fiction

There's no denying that Samuel L. Jackson was born to play Jules Winnfield. Quentin Tarantino even wrote the role specifically for the actor in hopes he would take it. But during casting, Tarantino was very impressed with an audition by Paul Calderon. Jackson caught wind of this and flew out to Los Angeles to meet with the director again. Jackson received the part, and went down in movie history as one of cinema's greatest hitmen, earning an Academy Award nomination in the process. So it's safe to say it was a wise decision.

Calderon still got a part of his own in Pulp Fiction, that of bartender Paul (who Vincent and Jules visit early in the film). Instead of being a star of the ensemble, Calderon became a side player. However, seeing him so warm and welcoming as Paul makes one wonder if he could have been intimidating enough to recite Ezekiel 25:17 with enough conviction to frighten even the most hardened criminals. Fortunately, Jackson was able to reach out to Tarantino and history was made.

Collateral

In Michael Mann's crime drama, the principal role of cab driver Max went to Jamie Foxx, who turned in an Oscar worthy performance. But the character evolved as the project was being developed. At first, the film's screenwriter wanted Robert De Niro to play the besieged taxi driver, an almost too-obvious callback to his iconic Travis Bickle role. However, De Niro was deemed too old for the part and other names were considered.

One actor who was heavily in the running was Adam Sandler, who went as far as to set up a meeting with Mann. But in the end, the director went with Foxx, which was probably for the best. Foxx's turn is one of the film's strongest assets, and while Sandler has turned in some fine dramatic performances (most notably in Punch Drunk Love), he doesn't quite fit the unassuming everyman persona that made Max so relatable. Foxx was able to convey that, and he's more diverse of an actor than Sandler.

Batman Begins

When Christopher Nolan was tasked with restoring the cinematic reputation of Gotham's Dark Knight, he knew he had to take his time finding the next Bruce Wayne. Christian Bale and his trademark growl became Batman for a new generation, but one of his many on-screen foes was in the running for the Caped Crusader. One name Nolan initially considered was Cillian Murphy, who of course went on to play Scarecrow in all three installments of the trilogy. His screen test left that much of an impression with the director that he couldn't resist casting him.

Murphy is a very talented actor, so we're not saying him as Wayne would have been a mistake. It's just that it would have made Batman Begins a very different film. Obviously, if Murphy was playing the title character, someone else would have had to bring life to Jonathan Crane. Since both Bale and Murphy delivered in spades, we'll take the reboot as is instead of wishing something else took place. While Scarecrow wasn't the franchise's most iconic villain, his turn was very well-received (and creepy). And Bale put his stamp on DC's icon, perfectly balancing the Mr. Wayne and Batman personas.

Back to the Future

When you look at Michael J. Fox, it's hard not to see Marty McFly, the lovable hero of Robert Zemeckis' Back to the Future. But when the director was first gearing up for production, Fox was unavailable due to his commitments to the sitcom Family Ties. Eric Stoltz was cast instead, and principal photography commenced. A few days into the shoot, Zemeckis realized Stoltz wasn't right for the role, thinking that he wasn't funny enough to play Marty. An agreement was made with the Family Ties team, and Fox balanced the schedules for both to take part in the film.

It's fortunate for movie fans that Fox possessed stellar time management skills. His performance is a big reason why Back to the Future works so well. Fox was able to embody all the necessary traits that made Marty such a memorable character and a beloved film figure of the era. He was heartfelt, confident, and humorous, crafting a protagonist who was cool and relatable at the same time. Credit Zemeciks for noticing this early on instead of sticking with Stoltz, which could have ruined the picture. Even the replaced actor agrees it was the right call.

Conclusion

As Hollywood looks to add more and more major blockbuster films to their upcoming slates, there will be a plethora of roles up for grabs that the best actors will be after. Whether an established A-lister nags some, or they go to unknowns plucked out of obscurity, whoever we see on the big screen is most likely not the only option for the part. Learning who the competition was is just part of the fun.

As always, our list is not meant to be all-inclusive, so be sure to share some of your picks in the comments below. And be sure to subscribe to our YouTube channel for more fun videos!