Explained
How do the X-Men become part of the MCU?
How do the X-Men fully join the MCU? The Mutant Saga theory - how Avengers: Doomsday and Secret Wars use the multiverse to make mutants native, and what the next era looks like.
The X-Men are confirmed for Doomsday (who’s in), but that raises a bigger question: how do mutants become a permanent part of the MCU? The Mutant Saga theory offers a clean answer - the multiverse does the heavy lifting.
The problem the theory solves
For 20 years, the X-Men lived in a separate film universe (owned by a different studio). Marvel now has the rights, but it can’t just declare “mutants were always here.” It needs an in-story reason to fold them in. Enter the multiverse.
The two-step bridge
Step 1 - Doomsday (the crossover). Legacy mutant actors appear as versions from a collapsing reality, crossing into the main MCU during the incursion crisis. This honours the old films while putting mutants on screen alongside the Avengers. See will the X-Men join the Avengers.
Step 2 - Secret Wars (the reset). When reality is remade (will the MCU reboot), mutants become native to the rebuilt timeline - no longer visitors, but a built-in part of the world’s history. That’s the launchpad for a dedicated Mutant Saga.
What the Mutant Saga could hold
- A new MCU X-Men team, recast for the long haul.
- Classic stories finally adaptable in-continuity (mutant persecution, Krakoa-style nation ideas, House of M).
- Mutants woven into Avengers stories from the ground up.
The uncertainty
Marvel hasn’t detailed the mechanics. The direction - mutants integrated via the multiverse and a reset - is well-supported; the specifics of casting and timing are open.
Our verdict
Likely. The multiverse is the perfect bridge, and Doomsday plus Secret Wars is the crossing. Expect the legacy X-Men here, and a fresh mutant era after the reset.