What to watch before Avengers: Doomsday

What is actually known

Worth being clear about the difference between confirmed and speculated, because most catch-up lists blur it.

Confirmed: the release date, Robert Downey Jr. as Doctor Doom, and a cast that includes returning MCU leads (Hemsworth, Mackie, Stan, Hiddleston, Rudd), the Fantastic Four cast from First Steps, and the Fox X-Men actors listed above. Trailer footage shown at Comic-Con features Doom against all three groups.

Not known: the plot. This list is built from the announced cast and the multiverse groundwork already laid in released films — not from knowledge of what happens. Anyone telling you exactly which films are "required" is guessing.

The multiverse spine

If you watch nothing else, watch these four. They are the thread Doomsday is picking up.

• Avengers: Infinity War and Endgame — the previous two Avengers films, and the last time the roster assembled.
• Loki, both seasons — the actual spine of the Multiverse Saga. The TVA, the branching timelines, and the setup for a multiversal threat.
• Doctor Strange in the Multiverse of Madness — introduces incursions, the collision of universes, which is the mechanism by which separate continuities can meet.

Why the Fox X-Men films are on this list

This is the part most catch-up guides miss. Patrick Stewart and Ian McKellen are not playing new versions of Professor X and Magneto — they are the actors from the Fox X-Men films, a continuity that ran from 2000 to 2020 and has never been part of the MCU.

Deadpool & Wolverine already established that the Fox universe exists and can be reached. Doomsday appears to be the payoff.

Three films give you what you need: X-Men (2000) and X2 for those characters at their best, and Days of Future Past, which is where that continuity does its own multiverse-and-timeline story.

The short version

If fifteen titles is too many: Infinity War, Endgame, both seasons of Loki, Deadpool & Wolverine, Thunderbolts and The Fantastic Four: First Steps. That is the current state of play plus the multiverse mechanics, and it is roughly half the time.

Then add the three X-Men films if you want the Stewart and McKellen appearances to mean something rather than just register as a cameo.

What you can safely skip

Most of Phase 4 and 5. Eternals, Moon Knight, She-Hulk, Ms. Marvel, The Marvels, Echo, Ironheart and the What If...? seasons have no announced connection to Doomsday.

The full essentials list covers the wider question of what the MCU actually requires.