The Marvel Cinematic Universe has come a long way from its humble beginning in 2008 to the end of Phase 4 with Black Panther: Wakanda Forever. As the franchise enters yet another era, it continues to build up to Avengers: Secret Wars, the ultimate culmination of the ongoing Multiverse Saga.
In its earliest years, Marvel used six projects to build the foundation of its universe, with this period lasting four years being dubbed Phase 1. Each of these films built up important characters, locations, and storylines that would come into play at later dates. Nevertheless, certain projects within Phase 1 proved to be more important to the MCU's overarching story as it built up to not only the formation of the Avengers but their ensuing battle with Thanos.
6 The Incredible Hulk (2008)
The Incredible Hulk is the second film set within the Marvel Cinematic Universe, marking the only appearance of Edward Norton's titular superhero prior to being recast with Mark Ruffalo for the character's subsequent appearances. The film was released only one month after Iron Man, though it earned far lower box office numbers, resulting in Marvel Studios' failure to greenlight any sequels, which would have also required the involvement of Universal Studios.
Other than the Hulk's appearance in future MCU projects, The Incredible Hulk contributed very little to the franchise's overall story. Until very recently, its supporting cast was completely forgotten by the franchise, leaving audiences wondering if the film was even canon. While many fans have come around to this Hulk film in recent years, it also remains one of the weakest installments in Phase 1. Nevertheless, with the re-emergence of characters like General Ross and Emil Blonsky, as well as the return of Tim Blake Nelson's Samuel Sterns in Captain America: New World Order, the importance of The Incredible Hulk continues to grow.
5 Iron Man (2008)
As the very first film in the Marvel Cinematic Universe, Iron Man introduced the world to Robert Downey Jr.'s Tony Stark, a portrayal that would quickly become iconic not only to the Marvel fandom but also in cinematic history. The film, while smaller in scale when compared to its many successors, remains one of the highest-regarded movies in the entire franchise.
While this Jon Favreau-directed film does much of the legwork to set up the MCU, it, more importantly, stands on its own two feet, focusing on being a good standalone film first and foremost. Instead of laboring to set up various story threads, Iron Man is heartfelt and impactful, causing the audience to invest in its isolated story. It is truly only in the now-iconic post-credit scene that the film begins to set up a larger universe.
4 Iron Man 2 (2010)
Iron Man 2 is the highly-anticipated successor to the original 2008 film, which was the surprise hit of the year upon its release. The film continues Tony Stark's story, this time pitting the superhero against Mickey Rourke's Whiplash, a villain whom many Marvel fans have chosen to forget. Though many of the same creative voices from the original film were present for this sequel, including director Jon Favreau, it received somewhat lukewarm reviews upon its release.
The film's principal criticism has been that it is trying to do far too much in fabricating a larger universe. Not only does Iron Man 2 continues Tony's journey, but it also is forced to introduce Scarlett Johansson's Black Widow and James Rhodes's superhero alter-ego of War Machine, all of which is dwarfed by an Avengers subplot in the background and a post-credit scene setting up the arrival of Thor. Ironically, much of the film's notorious franchise-building was either undone or fleshed out further in other films, making Iron Man 2 surprisingly unimportant to the larger MCU.
3 Thor (2011)
Thor took a massive departure from the previous three Marvel films, eschewing their grounded sensibilities in favor of a lofty kingdom of Asgardian gods, including Chris Hemsworth's eponymous character. Despite mixed reviews upon its release, Thor isn't a bad film by any means, introducing audiences to a whole new dimension of the MCU. The film was followed by three sequels, marking the first solo franchise within the MCU to reach four installments.
Aside from the introduction of Thor himself, this 2011 film also includes several characters that would be key to future installments of the franchise. Most notable of these is Loki, who has become a featured player in both the Infinity and Multiverse Sagas, not to mention the first villain the Avengers ever fought. Additionally, the introduction of Asgard proves to be a major stepping stone to the MCU's cosmic side, a dimension of the franchise that would be fleshed out further in future projects, such as Eternals and The Marvels. While perhaps ahead of its time for the MCU, Thor nevertheless gave audiences a taste of the supernatural events that would unfold in future phases of the franchise, taking a departure from reality and embracing the fantastical world of Marvel.
2 Captain America: The First Avenger (2011)
Captain America: The First Avenger is a superhero film disguised as a period piece depicting the events of the Second World War. The audience follows Chris Evans in the eponymous role as a skinny Steve Rogers becomes the symbol of his nation's struggle against the Nazis. The film served as the immediate precursor to the culmination of Phase 1, setting up the formation of the Avengers.
In addition to kicking off one of the richest character arcs in the MCU, The First Avenger also took major pains to set up the formation of Marvel's super-team. From its title to its ending and post-credit scene, everything about this film is meant to set up The Avengers. Moreover, Captain America's debut also features the introduction of the MCU's first Infinity Stone, the Tesseract, which would become vital to the franchise's story as the Infinity Saga began to unfold.
1 The Avengers (2012)
The Avengers was the culmination of the first phase of the Marvel Cinematic Universe. The film pulled together the events from the prior five installments of the franchise, uniting Iron Man, Captain America, Thor, Black Widow, Hulk, and Hawkeye onscreen for the very first--and far from last--time. The film was truly history in the making, becoming a worldwide hit that truly kicked off the golden years of the MCU.
The first Avengers film is paramount in understanding the full scope of the MCU. Not only does it feature the formation of Earth's Mightiest Heroes, but it also sets up the entirety of the Infinity Saga, introducing the Mad Titan Thanos in its mid-credits scene. Everything comes back to this first superhero team-up, which changed the scope of Marvel Studios and the film industry itself.