This story was originally written ahead of the release of Avengers: Infinity War and has been updated ahead of Endgame.
As Doctor Strange said in the last movie, "We're in the endgame now." All of Marvel's cinematic exploits for more than a decade have led up to this moment, and moviegoers have been waiting for nearly a year since the cliffhanger ending of Avengers: Infinity War to know what happens next. That film was only Part One of a story that is expected to have serious repercussions for the future of some of Hollywood's most successful characters. No matter what, Avengers: Endgame is going to be a huge deal.
A lot of people are stitching together every clue, leak and seemingly-innocuous statement from the cast to try to determine how Endgame will conclude. Many other people, though, don't know what the heck is going on. (Seriously, there's, like, a big purple guy from space... And Benedict Cumberbatch is a wizard or something... And is that a talking tree hanging out with a talking raccoon?)
It has taken 20 movies over the course of more than 10 years to reach this point, which is exciting for all of the fans who have been along for the entire ride but extremely intimidating for anybody looking to catch up.
So let's cut that list down a bit. Here are the movies you should probably watch (in order), the movies you can get by with a recap on, and the movies you don't actually need to watch at all.
Note: We're only talking about movies in the Marvel Cinematic Universe (the shared world in which these stories all take place), which essentially boils down to movies released by Marvel Studios and Disney, which nixes Marvel character movies produced by other studios. That means no X-Men (sorry, Deadpool and Logan), no Fantastic Four (sorry, heroes that can't seem to get a good movie) and no Ang Lee's Hulk.
You should watch:
Captain America: The First Avenger
The subtitle The First Avenger isn't lying. Captain America's story begins in World War II, and it presents the dawn of superheroes as we know them. Importantly for Endgame, it introduces two very key players: Captain America himself and Bucky Barnes.
Where the Marvel Cinematic Universe began. A lot has changed since Iron Man was released, but it's important as the story that kicked off everything that lead to this epic superhero team-up in the first place.
To truly appreciate what this team will go through in Endgame, you have to see how the gang got together in the first place.
Guardians of the Galaxy
If you had any doubt about Marvel's meticulous roadmap to Endgame, just look at the blatant seeds they were planting in this movie from 2014. One of Marvel's weirdest and yet most charming movies so far, this hilarious sci-fi adventure not only introduces you to an important band of heroes, it also starts talking directly about the Infinity Stones -- which, surprise!, were at the very center of Infinity War and likely will be important in Endgame as well.
Captain America: The Winter Soldier
Beyond being one of the best movies in the Marvel Cinematic Universe, Winter Soldier moves a lot of pieces and introduces important developments for key characters.
While not as memorable as its crossover predecessor, Age of Ultron introduces several heroes and, more importantly, begins to show the cracks in their armor.
An Avengers movie in all but name, Civil War pits several of Earth's greatest heroes against each other and stresses the ideological differences between the Avengers' leaders: Iron Man and Captain America. It's also your introduction to Spider-Man, who got a lot of screen time in Infinity War.
While Doctor Strange stands alone better than most of Marvel's films, it's important to Endgame primarily because of its title character. Dr. Stephen Strange is one of the Marvel universe's most powerful figures, and knowing how his powers work could help make sense of the action.
Black Panther took the world by storm and became one of the highest-grossing films of all time when it was released earlier this year. While its title character was introduced in Captain America: Civil War, you learn more about him -- and his homeland of Wakanda -- here. Make sure you stay for the post-credits scene.
I mean, this one should be obvious, right? Infinity War is Part One to Endgame's Part Two. It is without a doubt the most important movie to watch before the climax. That said, it's also one of the most enjoyable, so this would have been an easy recommendation regardless.
While her debut movie doesn't dovetail into Endgame quite the same way Infinity War does (given the fact that it takes place in the '90s), Captain Marvel is poised to become a huge freakin' deal in the Marvel Cinematic Universe going forward. You should know where she came from and how her powers work, because she likely has a big role to play in the fight with Thanos. (Also, the movie is highly enjoyable as a standalone superhero story.)
You should read recaps of:
You'll probably have a good idea about what the God of Thunder and his brother, Loki, are all about just by watching the Avengers movies, but you still might want to brush up on his powers, his family and his history.
There here are some details about Gamora's parentage that are important to Infinity War and Endgame, but they get summarized with the most important facts. A good movie, but you can read the highlights if you're strapped for time.
You need to know how Ragnarok ends, but you don't necessarily need to be along for the psychedelic ride that leads up to it, great as it may be. You do want to know about its final moments, though, as Infinity War picks up right where Ragnarok leaves off.
Unlike Infinity War (where Ant-Man was barely even referenced), it seems that Scott Lang will have a big role to play in Endgame. Depending on who you ask, it's highly possible that important story elements from Ant-Man and the Wasp (specifically the Quantum Realm) will be extremely important to defeating Thanos in Endgame, but even if so, you can probably skate by with just a recap on this one. (It's a good movie, though. Watch it sometime!)
You can skip:
(Note: By saying you can skip the following Marvel movies ahead of Endgame, I do not mean that they are bad movies.)
All the TV shows
There have been some great Marvel shows lately that nod to the Marvel Cinematic Universe, but they don't explicitly affect the bigger sandbox. Agent Carter, Agents of S.H.I.E.L.D. and the Netflix shows (Daredevil, Jessica Jones, Luke Cage, Iron Fist, The Defenders and The Punisher) are all fun in their own right, but not important to the Infinity War discussion.
The Incredible Hulk
While technically part of the MCU, this Hulk movie doesn't even feature the same actor that plays the Hulk today. Even Marvel itself seems to forget that this movie exists, so you can, too.
Iron Man 2
It's OK, but it's not important.
Iron Man 3
One of the lower points in the Marvel movie pantheon, which, granted, still puts it above many other superhero movies throughout history.
Thor: The Dark World
You don't even need to see Thor 2 to enjoy or understand Thor 3. That's how little this one mattered.
Against all odds, Ant-Man is a wonderfully amusing heist comedy that's highly enjoyable to watch. That said, you learn all you need to know about the titular character via his cameo in Captain America: Civil War, making this movie skippable.
Like Ant-Man, you get all you need to know about Spider-Man from Civil War. Homecoming is a great film about the webslinger, and it tells a wonderful story about a high school kid fighting neighborhood crime, but it isn't necessary for your Avengers viewing.