The MCU is undoubtedly one of the biggest cinematic achievements of all time. The 22-film story arc is an unheard of feat, requiring unbelievable planning and execution to pull it off. One of the most impressive aspects of the cinematic universe has been the amazing quality of actors they have added to their roster over the years. The star power that is one display in some of the scenes in Avengers: Endgame, for example, is mind-blowing.

RELATED: 10 Actors You Forgot Appeared In MCU Movies

It's hard to imagine other actors in some of the roles that have become so iconic, but there were plenty of alternate possibilities to the MCU's biggest roles. In Phase 1 especially, some of the actors who were considered could have changed the look of the franchise forever. Here are some of the actors who were almost cast in roles in Phase 1 of the MCU.

Stuart Townsend As Fandral

Stuart-Townsend-Aragorn-Replaced

Fandral is far from one of the most prominent characters in the MCU which could explain the last minute recasting for the role. The dashing swordsman who is one of Thor's closest allies and a member of the Warriors Three was originally to be played by Irish actor Stuart Townsend until he left the role due to creative differences.

This isn't the first time Townsend was nearly in a massive fantasy franchise as he was originally cast as Aragorn in Lord of the Rings as well. The role of Fandral also went through some changes over the franchise's history as Josh Dallas vacated the role after the first Thor and was replaced by Zachary Levi in Thor: The Dark World and Thor: Ragnarok.

Sam Rockwell As Iron Man

Justin Hammer speaking at the senate hearing in Iron Man 2

Sam Rockwell is one of Hollywood's most talented character actors. He is the kind of performer that seems just as effective in indie projects as he does in big budget films. However, he could have had a very different career if he had auditioned for Iron Man like it was initially planned.

RELATED: Avengers: Endgame Almost Had Iron Man Drop the MCU's First F-Bomb

Rockwell claims Jon Favreau reached out to him about screen testing for the role but that nothing came of it. He himself theorizes once they saw Robert Downey Jr's audition the process was over. However, Favreau obviously kept him in mind as Rockwell eventually joined the MCU as Justin Hammer in Iron Man 2.

John Krasinski As Captain America

There was a time when the thought of Jim Halpert from The Office starring in a superhero film would be a laughable idea. However, John Krasinski has been showing he is a solid action hero in recent years with 13 Hours, Jack Ryan and A Quiet Place. So maybe it makes sense he was a strong contender for Captain America.

Krasinski says he actually got to the point of putting on the iconic costume but when he saw Chris Hemsworth show up, he quickly decided he wasn't ready to be a superhero. Chris Evans perfect the role of Cap and Krasinski's career has done just fine without the part.

Emily Blunt As Black Widow

Emily Blunt in Edge of Tomorrow

The MCU was almost a family affair as Krasinski's wife, Emily Blunt, was nearly cast in the role of Black Widow. Blunt was said to have been offered the role for the character's first appearance in Iron Man 2, however, the dreaded scheduling conflicts got in the way. Even more disappointing was that she had to pass on the role in favor of Gulliver's Travels.

Even without the Black Widow role, Blunt has played quite a few badasses over the years and become one of Hollywood's most popular actors. Of course, Scarlett Johansson took the part and has been a key part of the MCU ever since.

Timothy Olyphant As Iron Man

Timothy Olyphant might not be the biggest movie star in the world, but he has been involved in some of the best television series in the 21st century. Olyphant proved to be a badass hero in shows like Deadwood and Justified, and he recently showed off his exceptional comedic chops in Santa Clarita Diet. Had he landed the role of Iron Man, he might had to leave the television world behind.

Olyphant claims that he auditioned for the role on the same day as Robert Downey Jr. and he says he's still waiting to hear back if he got the part. Obviously, he's able to joke about it, but there was probably no actor around who could have taken that role from Downey Jr.

Liam Hemsworth As Thor

Star Wars: Han Solo Fan Casting - Liam Hemsworth

It's pretty remarkable that two brothers from Australia could make it in show business to the point that they are both vying for the title role in a massive superhero film. It is even more remarkable that the role came down to a choice between the two Hemsworth brothers.

RELATED: Thor: Ragnarok Is Quentin Tarantino's Favorite MCU Movie

Chris Hemsworth has said that he had auditioned for the role but had been passed over in favor of his younger brother Liam. But before the deal was done, Chris was given another shot and he locked down the role. Luckily, the brothers hold no ill-will and Liam has continued to have a solid career of his own.

Mel Gibson As Odin

Mel Gibson In Daddy's Home 2

Mel Gibson has had a rocky career over the years. He was one of Hollywood's biggest stars in the 80s and 90s but his controversial personal life has made Hollywood hesitant to cast him in recent years. Despite all this, Gibson could have had a major role in one of the biggest franchises of all time.

Gibson confirms he was approached to play Odin in the Thor films but turned it down for unspecified reasons. Gibson has focused on directing in recent years which could explain his decision. Acting legend Anthony Hopkins took the role and brought his usual gravitas to the part.

Alexander Skarsgård As Thor

Alexander Skarsgård Tarzan

Alexander Skarsgård has had a solid career of a mix of big budget films and small indies. He is a charismatic and talented actor with the look of an action hero, so it's not too surprising he has been linked to a few superhero roles. But the one he seemed to be a pretty perfect fit for was the God of Thunder.

Skarsgård says he spoke to Kevin Feige and director Kenneth Branagh about the part and even did a costume fitting. Of course, Chris Hemsworth proved to be even more ideal for the part. In another example of a family affair, Alexander's father, Stellan Skarsgård played Erik Selvig in the MCU.

Mark Ruffalo As The Hulk

Remarkably, there have been very few cases of recasting in the MCU, but one of the most significant was certainly when Edward Norton stepped away from the role of Bruce Banner/Hulk. Norton played the role in The Incredible Hulk and apparently had many creative differences during production. Instead of returning to the role in The Avengers, Mark Ruffalo was cast instead.

RELATED: Why Hulk Never Got His Rematch With Thanos in Endgame

Interestingly, Ruffalo has the first choice for the role in The Incredible Hulk. If director Louis Leterrier had gotten his way, MCU fans could have finally stopped ignoring the fact that The Incredible Hulk exists, or pretending that Norton and Ruffalo look anything alike.

Dane Cook As Captain America

Dane Cook Good Luck Chuck

It's impossible to say if casting is good or bad until you see the actual movie. Famously, fans were against Heath Leger's casting as Joker in The Dark Knight and see how that worked out. However, when it comes to Dane Cook almost playing the role of Captain America in the MCU, we are pretty confident things worked out for the best.

The extremely successful comedian even lost a good deal of weight to audition for the superhero role. But when he took to Twitter to announce his audition, Cook claims he upset some of the Marvel people. Cook has made a great career as a comedian but it's clear Evans was the right man to play Cap.

NEXT: MCU: 10 Phase 1 Moments That Foreshadowed Endgame