X-Men MCU theory reveals Marvel's most important movie isn't what you think

How will the X-Men join the MCU? It’s a question we’ve been pondering ever since Kevin Feige confirmed “mutants” were coming to the Marvel Cinematic Universe back at Comic-Con 2019. There’s no shortage of theories either, from rumors that Doctor Strange could find the X-Men somewhere in his multiverse of madness to speculation that Thanos accidentally created mutants when he snapped his fingers. But one compelling new theory argues that the most important Marvel movie for X-Men fans isn’t the one you think.

On the MCU Theories subreddit, one X-Men fan recently laid out three popular options for how mutants could make their way into the Marvel Cinematic Universe. However, the most interesting option comes from a comment shared by redditor u/HandBanana666, who points out that in the comics, the origins of the X-Men can actually be traced back to the Celestials, who coincidentally are set to make their first major on-screen appearance in Eternals this November.

“They do have a cosmic origin in the comics,” writes u/HandBanana666. “The X-gene was created by the Celestials.”

Did the Celestials create the X-Men?

A quick bit of research confirms this is true. The Celestials were invented by Jack Kirby in 1976. Originally introduced in Eternals #1, the Celestials are the oldest and most powerful beings in the multiverse. They’re also responsible for creating both the Eternals and their arch-enemies, the Deviants, by meddling with the genetics of the ancient bipedal apes who went on to become humans.

Four years later, tucked into What If Volume 23, Marvel revealed a new wrinkle in the story of the Celestials and their experiments on early man. Not only did they create Eternals and Deviants, but it’s possible they also created the X-gene that manifested thousands of years later to turn some humans into “mutants.”

Written by Mark Gruenwald with art by Ron Wilson and Chic Stone, “The First Celestials Host” is a canon story which reveals that when the Celestials visited Earth, they left a “latent gene” in humans that wouldn’t manifest itself for thousands of years. The word “mutants” is never said outright, but the implication seems pretty clear.

So will Eternals make this story a part of the MCU? The clues are already all around us.

The Eternals and the X-Men

In the trailer for Eternals, they refer to something called an “Emergence.” This is some sort of event so disruptive the Eternals are forced to break their own promise never to interfere with humanity. Could the Emergence have something to do with mutants?

In the comics, one Celestial named Tiamut is actually sleeping within the Earth — until the Dreaming Celestial wakes up. It’s been theorized that his powers could be seeping out and causing all sorts of abnormal occurrences. If this is the Emergence in Eternals, then Tiamut might explain not just the X-Men but also the general increase in the number of superheroes in the MCU since it began in 2008.

When Tiamut finally does emerge, it could unleash an incredible wave of energy that activates latent X-genes around the world, ushering mutants into the MCU in one fell swoop.

This Marvel movie theory could also help explain everything from where the Scarlet Witch’s powers come from to how Bruce Banner survived the radiation blast that turned him into the Hulk. We’re not saying every superhero in the MCU has the X-gene, but if a few of them already did, it could explain a lot.

And if this theory is true, we should know pretty soon. By the end of 2021, mutants might be as important to the Marvel Cinematic Universe’s future as the Infinity Stones were to its past.

Eternals hits theaters on November 5, 2021