The finale of the Infinity Saga -- everything in the Multiverse Saga responds to it.

Directly responsible for branching the multiverse the entire saga runs on.

The clearest on-screen merge of the Fox X-Men universe into the MCU -- Wolverine carries straight into Doomsday's ensemble.

The foundation for the Fox-era X-Men line-up that matters going into Avengers: Doomsday.

Deepens the Fox-era X-Men team and relationships carried forward into Doomsday.

Directly forms a team expected to matter in Doomsday.

This Earth and its heroes are confirmed to collide with the mainline MCU in Doomsday.

Every thread in the modern MCU -- Stark tech, the Avengers Initiative, the post-credits stinger format -- traces back here.

Sets up Nick Fury's Avengers Initiative plans.

Foundational for every cosmic/Asgardian thread that follows.

The template for every Avengers film since, including Doomsday.

Deepens Tony's arc heading into Age of Ultron.

Reshapes the entire political landscape of the MCU going forward.

The Quantum Realm becomes critical machinery in Endgame.

The fallout defines every Avenger's arc through Endgame.

Doctor Strange becomes central to the entire Multiverse Saga.

Deepens the team dynamic ahead of Infinity War.

Sets up Peter's arc through No Way Home.

Directly sets up Thanos's attack at the start of Infinity War.

The single most consequential event in the Infinity Saga.

The Quantum Realm mechanics here matter directly to Endgame's plot.

Explains how Fury calls in reinforcements at the end of Infinity War.

Its ending directly triggers Spider-Man: No Way Home.

Directly sets up Wanda's role in Doctor Strange 2 and introduces Agatha.

Sets up Sam's Cap identity ahead of Brave New World.

The direct catalyst for Doctor Strange in the Multiverse of Madness.

Sets up both the Echo spin-off and Kate Bishop's future in the MCU.

Confirms the multiverse is unstable and dangerous -- core to everything after.

Directly sets up her role alongside Carol Danvers in The Marvels.

Closes out Thor and Jane's arc; lighter stakes for the wider saga.

Establishes the new Black Panther and Wakanda's future role.

Kang was set up as the Multiverse Saga's central threat here.

The team disbands here, reshaping who's available going forward.

Directly follows up Ms. Marvel and WandaVision's Monica Rambeau arc.

Directly connects to Thaddeus Ross's arc heading into Doomsday.

Introduces Simon Williams (Wonder Man) and brings back Trevor Slattery from Shang-Chi.

Sets up Frank Castle's state of mind heading directly into Spider-Man: Brand New Day.

The mainline Spider-Man's most recent chapter, heading straight into Doomsday.

Concludes Vision's arc right before the multiverse collides in Doomsday.

Rarely referenced later; safe to skip if you're short on time.

Establishes Cap, Bucky, and Hydra -- all central to later Phases.

Mainly useful for Infinity Stone completionists.

Background for the Guardians team that fills out Infinity War's cast.

Vision and Wanda are central to Phase 4's Disney+ shows.

Wakanda is central to Infinity War, Endgame, and Wakanda Forever.

Introduces Yelena Belova, who becomes a Thunderbolt.

The Ten Rings' true origin is a dangling thread the saga may still pick up.

Mostly self-contained, though it expands the MCU's cosmic scale.

Fun multiverse detours; not required to follow the main plot.

Largely stand-alone so far, but expands the pantheon side of the MCU.

Pure fun; no bearing on the main plot yet.

Mostly self-contained; a fun tonal outlier.

Pure fun; skippable for plot purposes.

Shakes up SHIELD/Skrull relations; light connective tissue.

Charming, but entirely optional side content.

Deepens the Kingpin/Daredevil corner of the MCU.

Expands the MCU's magic system introduced in WandaVision.

A fun side story rather than required viewing -- it doesn't feed into the mainline plot.

Ties the Netflix-era Daredevil corner more tightly into the mainline MCU.

Introduces a young inventor who may factor into future team-ups.

Expands Wakanda's history but doesn't connect to the present-day plot.

A self-contained horror detour; skippable for the main story.

Comes after Doomsday, not before it -- not required for this catch-up guide, but included here for a complete library.

The event this entire catch-up guide exists to prepare you for.