The Marvel Cinematic Universe, or the MCU, is split up into phases that each represent a general era in this massive superhero movie timeline. Phase 1 saw the core Avengers get together, while Phase 2 introduced many new parties and added outer space adventures. Then Phase 3, the longest and arguably best MCU phase, deepened and changed the MCU even more.
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Character introductions, character deaths, new locations, new abilities, and personal drama helped define the MCU's third phase and completely changed the landscape of this superhero saga forever. Phase 3 started with a bang in 2016's Captain America: Civil War, which changed a lot up front, and by the time Endgame was over, the MCU was almost unrecognizable.
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10 Black Widow Was Written Out For Good
It's true that Natasha Romanoff finally got her own standalone movie in the MCU's fourth phase, but as a prequel. Chronologically, Black Widow was written out of the MCU in 2019's The Avengers: Endgame, where she gave her life to help Hawkeye get the Soul Stone on Vormir.
Rarely does the MCU permanently kill off its heroes, since fans want to see those superheroes return later for more adventures. Writing out Black Widow robbed the MCU of a powerful female character, but fortunately, new heroes like Shuri and Ironheart are ready to pick up the slack.
9 Wakanda Became An Important Location
Starting in 2010's Thor, the MCU has been adding many exotic new locations, nations, and even planets to its world, such as Sokovia in 2015's The Avengers: Age of Ultron and planets like Xandar and Morag in the Guardians movie. Phase 3 also added the hidden African nation Wakanda, a location many fans were eager to see.
Wakanda was mentioned by name in Civil War, and in 2018's Black Panther, the wealthy nation came to the fore and wowed MCU fans with its rich culture and abundant vibranium. Fans got to see more of Wakanda in 2018's The Avengers: Infinity War and 2022's Black Panther: Wakanda Forever.
8 Captain America Was Written Out
Captain America has been a key player in the MCU since Phase 1, and his character arc took many exciting twists and turns regarding his friend Bucky Barnes, his feud with Tony Stark over the Sokovia Accords, and more. His final adventure came in Endgame, and then he said goodbye.
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Iron Man's death left a huge hole in the MCU, and just moments later, moviegoers saw another hole open up when Captain America chose to stay in the 1940s to resume his old life with Peggy Carter. Now it's up to Sam Wilson to carry that shield and become the new Captain America.
7 Time Travel Became Possible
Even if the Avengers are unlikely to actually attempt time travel again anytime soon, the MCU's third phase still established time travel as a feasible course of action. The surviving Avengers hit a wall when Thanos used the Infinity Stones to destroy those same stones, but then Ant-Man/Scott Lang came along.
With careful use of Pym Particles and the bizarre quantum realm, the Avengers could go through time and choose specific locations and years to visit. That helped them reset the flow of time and defeat Thanos for real, ensuring that almost every Avenger could survive to see Phase 4.
6 The Avengers Split Up
The MCU was forever changed early in Phase 3 when the villainous Baron Zemo concocted a plan to turn Captain America and Iron Man against one another, mostly with Bucky Barnes. Zemo's plan worked, and even if Cap and Iron Man made up later, the Avengers team was ruined.
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This meant Earth had fewer defenders on hand when Thanos and his loyal followers arrived in Infinity War, and Bruce Banner was shocked to hear that Cap and other Avengers were not available to help. The Avengers team may eventually come back together, but it's a difficult process.
5 Smart Hulk Was Introduced
In the MCU's first two phases, the scientist Bruce Banner was like Dr. Jekyll and Mr. Hyde, switching between his gentleman form and his monster form, but the MCU's third phase tweaked the formula. The Hulk lost badly to Thanos in Infinity War's first scene, then refused to come back.
After the Snap, Bruce Banner came to accept his Hulk side for real, and blended his two halves to become Smart Hulk. This was a new era for the Hulk and made him more reliable, though it may come at the cost of some of his strength, a price Bruce is clearly willing to pay.
4 Celestials Were Introduced
The second Guardians movie added and changed several characters, with Yondu Udonta and Nebula both being redeemed while Mantis and her Celestial boss Ego were introduced. Ego, as a Celestial, added a wild new element to the MCU, representing an ancient "elder race."
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Ego died in the second Guardians movie, but his introduction still changed MCU fans' perception of Star-Lord/Peter Quill. This also helped lay the groundwork for the Phase 4 movie Eternals, with the Eternal race having a close link to the incredible Celestial race.
3 Tony Stark Was Written Out
Tony Stark was another key player in the MCU, and most fans consider his 2008 standalone movie to be the MCU's start. Iron Man helped defend NYC from the Chitauri army, then made and helped defeat the villainous robot Ultron near the end of Phase 2.
Iron Man defended the Sokovia Accords in Civil War, then led Earth's defense in Infinity War, only to lose to Thanos on Titan. In Endgame, Iron Man made the sacrifice play and gave his life performing a Snap with the Infinity Stones, and he was given a hero's burial when the war was won. Now it's up to Shuri and Ironheart to fill the void.
2 Bucky Barnes Was Redeemed
In Phase 1, Captain America's friend Bucky Barnes seemingly died in World War II, only to return in Phase 2 as the brainwashed Winter Soldier. He was an antagonist, but Captain America was convinced that his old friend was buried in the Winter Soldier's mind, waiting for rescue.
Phase 3 completed Bucky's arc, with the real Bucky Barnes emerging in Civil War and fighting to defend Wakanda in Infinity War. He returned in Endgame alongside the rest of the fallen as a righteous hero, setting him up for more adventures as his old self later in the MCU.
1 Magic & Sorcerers Appeared
In its first two phases, the MCU was mostly all about advanced technology and science, from Iron Man's suit to spaceships to the gamma rays that turned Bruce Banner into the Hulk. The supernatural was just an afterthought until Phase 3 ushered in Doctor Stephen Strange.
Doctor Strange, the Ancient One, and Wong all made magic glamorous and relevant in the MCU, and some victories would have been impossible without sorcery. Doctor Strange fought off Dormammu, for example, and magic portals allowed the fallen Avengers and allied armies to confront Thanos' army on Earth in Endgame.
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