The Marvel Cinematic Universe is one of the most monumental film franchises in history, cemented by its cast of Avengers - but they weren't all the only people to be considered for their respective parts. The box office juggernaut has churned out 23 movies to date with a slew of new titles on the way. At the core of the franchise is its list of headlining cast members who have taken on the portrayal of popular superheroes, the Avengers being the most prominent. Though the Avengers team has grown in recent years, it started out as six brave members.

When the MCU was first forming, the studio took years to lay out the foundation with a few standalone movies to introduce viewers to their biggest figures. Between 2008 and 2011, the franchise effectively put Iron Man, the Hulk, Thor, and Captain America in the spotlight while also introducing names like Black Widow, Hawkeye, and many others. This was all buildup to the MCU's first major viewing event with the release of The Avengers in 2012.

Related: Marvel Movie Delays Are What MCU Should’ve Been After Endgame

By the time The Avengers was released, moviegoers were familiar with the primary characters played by actors Robert Downey Jr., Chris Evans, Chris Hemsworth, Scarlett Johansson, and Jeremy Renner. The only new actor to join the mix as an Avenger was Mark Ruffalo. It was a very long process in putting together this stellar cast, since many other names were considered for these coveted roles. That said, here's every big actor that could have been cast as an original member of the Avengers.

Tony Stark / Iron Man

Plans for a big-screen Iron Man adaptation began in 1990 and in the decades that followed, the film rights bounced from studio to studio. In that time, Nicolas Cage shared his interest in portraying the titular superhero and rich playboy, Tony Stark. Since the film never gained enough momentum, the actor missed out on the chance. By 2005, Marvel received the rights to the character and developed a project from scratch. Jon Favreau signed on to direct the movie a year later and he was tasked with finding the perfect actor to portray Tony. In the early stages, Favreau wanted an unknown actor in the role but that decision quickly changed.

A few well-known actors have revealed that they auditioned for the coveted role which would go on to pave the way for the rest of the MCU. Tom Cruise was considered but didn't get very far in the audition process. The same could be said for Timothy Olyphant, who also scored an audition in the 2000s. Even Hugh Jackman was considered, which might be surprising since he was already in the midst of portraying Wolverine, another Marvel character. Lastly, Sam Rockwell threw his hat in the ring, and although he didn't get the gig, he later received the chance to play the villain Justin Hammer in Iron Man 2. In the end, Robert Downey Jr. emerged as the ideal candidate to play Iron Man. The actor's performance in Kiss Kiss Bang Bang is what truly sealed the deal, especially in the eyes of Favreau. Downey then effectively led the MCU for the next decade-plus and helped grow the franchise into what it is today.

Related: The Iron Man 1 Scene That Has A Hidden Robert Downey Jr. Meaning

Thor

Chris Hemsworth as Thor MCU

Developing a Thor film was another idea that took off in the 1990s. The adaptation eventually fell back into the hands of Marvel and Kenneth Branagh signed on to direct. When the God of Thunder was being cast, Chris Hemsworth wasn't the producers' first choice for the role. In the early stages, Daniel Craig was offered a chance to play the Asgardian but he was forced to turn it down due to his ongoing commitments with the James Bond franchise.

A handful of other popular names auditioned for Thor. Those actors included Charlie Hunnam, Alexander Skarsgård, Channing Tatum, and Joel Kinnaman. Chris' younger brother, Liam Hemsworth, also tried out for the role but was passed over. Professional wrestler Paul Levesque (aka Triple H) was another name and although his physique passed the test, his level of acting wasn't up to the required standards. After a bit of a back-and-forth, Chris Hemsworth emerged as the front-runner and went on to become a fan-favorite among the MCU. His time in the franchise is still far from over with another solo movie, Thor: Love and Thunder, on the way in 2022.

Steve Rogers / Captain America

Chris Evans flying a plane in Captain America The First Avenger

Steve Rogers was first introduced into the MCU with 2011's Captain America: The First Avenger. It served as the fifth movie in the franchise and the last movie before The Avengers debuted. Chris Evans was cast in the role and the actor went on to appear in 11 MCU installments to date, some through cameos and others in starring roles. Before getting the role of Steve Rogers, Evans portrayed another Marvel character, Human Torch, for the Fantastic Four series. In fact, the actor declined the role of Captain America multiple times before signing the multi-picture contract. If Evans kept declining, Marvel Studios had a few other actors in mind.

A long list of actors tried out for the lead role including Channing Tatum, Garrett Hedlund, Dane Cook, Alexander Skarsgård, Jensen Ackles, Scott Porter, and Mike Vogel. Sam Worthington and Will Smith were said to get the farthest in the casting process. Two other names that were linked to the role were Ryan Phillippe and John Krasinski. Fans have been vying for Krasinski to get a role in the MCU and there's still hope for future installments. Sebastian Stan also made his MCU debut in The First Avenger, and before he won the part of Bucky Barnes, the actor first auditioned for the titular role. As for Evans, he may longer be Captain America, but he will also be the MCU's Steve Rogers.

Related: The Incredible Hulk’s Captain America Scene Explained (& Why It Was Cut)

Bruce Banner / Hulk

The Hulk was the second character to get a solo film in the MCU but his path since then has been a little rocky. After the 2003 film, Hulk, starring Eric Bana in the lead role, the film rights to the character went back to Marvel. They decided to develop another adaptation, The Incredible Hulk, which served as the second installment in the MCU. This time around, Edward Norton portrayed the role of Bruce Banner and was even set to reprise the role for 2012's The Avengers. Unfortunately for Norton, negotiations broke down and the role was recast.

Before Mark Ruffalo took over the role of the Hulk in 2012, the actor was considered for Louis Leterrier's 2008 film but lost out to Norton. When it came to The Avengers, Marvel decided they wanted to go in a new direction with Bruce Banner on a creative level. This meant moving on from Norton and bringing on a new face to a franchise. Casting Ruffalo was clearly the right choice since the actor has appeared in seven installments to date (including cameos).

Natasha Romanoff / Black Widow

Black Widow strikes a superhero pose in Iron Man 2

Black Widow remains as one of the few members of the original Avengers to have their own solo MCU film. That was supposed to change with the release of Black Widow in May but due to the recent theatrical delays, the movie will now hit theaters in November. Black Widow, aka Natasha Romanoff, was first introduced in the franchise with Iron Man 2. Marvel wasn't just tasked with filling the role for that movie, but they also needed a suitable actress for the long-term. Scarlett Johansson has notably played the role for over a decade but she wasn't the first actress to receive an offer.

The actresses who were considered for the 2010 film include Jessica Biel, Gemma Arterton, Jessica Alba, and Angelina Jolie. Eliza Dushku also campaigned for the role but it's not clear if she ever auditioned. Another actress that auditioned was Natalie Portman who missed out on the role but was later cast as Jane Foster in Thor. Marvel entered talks with Emily Blunt to take on the role of Black Widow but the actress had to turn down the offer due to other commitments. Like her husband, John Krasinski, Blunt's name repeatedly comes up when new characters are being cast for the MCU.

Related: John Krasinski and Emily Blunt Should Lead Marvel's Fantastic Four

Clint Barton / Hawkeye

Clint Barton was the least known member of the Avengers to be featured in the first team-up film. The character of Hawkeye won't be starring in a solo movie, but a TV series focused on the superhero is in development at Disney+. Hawkeye first appeared in Thor through an uncredited cameo. Jeremy Renner portrayed the minor role but it was no guarantee that he was set to reprise the role in The Avengers.

When Marvel was still planning the arc for Hawkeye in the MCU, Jensen Ackles was the name highly considered. The studio liked Ackles when he auditioned for Captain America so his name was shortlisted for future roles. The actor couldn't take on the major role due to his scheduling with Supernatural so Renner became the face of the skilled archer.

Next: Worst MCU Movie? Why Marvel Has Never Made A Bad Film

Key Release Dates