There's only one MCU movie you absolutely need to rewatch before seeing Avengers: Endgame. In its decade-plus existence, the Marvel Cinematic Universe has become an unruly franchise to follow. With so many heroes and disparate story threads, taking in both Earth and the cosmos themselves, there's a lot to take in and remember for each passing installment.

Every crossover so far, from The Avengers and Avengers: Age of Ultron to Thor: Ragnarok, has demanded some amount of fore-knowledge to really understand where the characters are and why the story being told matters. Sure, they don't go out of their way to alienate audience members not totally up-to-date, but to really get a sense of theme, character arcs, and stakes, it helps to have previous MCU movies fresh in your mind. For Avengers: Endgame, the culmination of all three phases of the MCU, the idea would be to rewatch everything from Iron Man in 2008 onward to soak in the journey to this point. That's two dozen movies, so not exactly an easy thing to carve out time for, and although Avengers: Endgame is the big showdown between the Avengers and Thanos, it's not altogether necessary.

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The only film necessary to rewatch before Endgame is Avengers: Infinity War, the direct prequel from last year. Infinity War brings Thanos into the fold, fleshes out what the Infinity Stones are and why they matter, and gives a satisfactory refresher on newer heroes like Doctor Strange and Black Panther, with half the film taking place in the latter's home country of Wakanda. More importantly, it ends with Thanos perpetrating the snap, the event that wiped out half of all life in the universe that our heroes are now working to reverse. Avengers: Endgame is part two of this story – in fact, the initial plan was for these to be titled Avengers: Infinity War Part 1 and Part 2 - and they were filmed back-to-back, so they've always been intended as a double-feature.

Of course, Thanos and the Infinity Stones have had a lingering presence going right back to the early days of the franchise. The Tesseract, containing the Space Stone and recently seen again in Captain Marvel, was introduced in the post-credits scene of Thor and was a pivotal aspect of The Avengers, where we got our first look at Thanos as the franchise's main villain. Throughout the MCU, there have been all sorts of hints, nods, and references - some more direct than others - to these mysterious, all-powerful objects as well as Thanos' plan.

It helps to understand what the protagonists have been through up to this point, too. Captain America: Civil War, directed by Endgame directors Joe and Anthony Russo, shows why Steve Rogers and Tony Stark aren't on speaking terms anymore, and Thor: Ragnarok explains Thor, Hulk, and the remaining Asgardians being on a spaceship at the start of Infinity War. Both Guardians of the Galaxy and Guardians of the Galaxy Vol. 2 deal with Thanos as a cruel, abusive father-figure, and explore the scale of cosmic Marvel, while Thor: The Dark World and The Avengers are also important for introducing Infinity Stones.

Watching even select films couches the events of Avengers: Endgame in a wide context that's been slowly built-out over time, but none are crucial to the exact plot of this final showdown for the original six members of the Avengers Initiative. For that, only one is absolutely a must-see, and that's Avengers: Infinity War.

Next: The Best MCU Rewatch Order For Before Avengers: Endgame

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