The Marvel Cinematic Universe has been a pretty straightforward place to this point, but that looks like it will change soon. Between Loki's mention of a past multiversal war, the upcoming Doctor Strange In The Multiverse Of Madness, and all the stuff happening in Spider-Man: No Way Home, it seems the multiverse will soon play a key part in the shared universe.
We've talked a lot about how that could happen and how it could help explain away some of the problems associated with re-introducing legacy heroes to the MCU, but we haven't talked about another interesting benefit to this. Over the years, Marvel Comics has used the multiverse to introduce alternate identities to beloved characters or even establish entirely new ones. The following are the characters born from those efforts that it'd be great to see included in the MCU, for very good reason.
There's a litany of Spider-Man characters in the multiverse, and they're about the strangest of the bunch. Of course, I know there's a lot of Miles Morales fans who would love to see the character debut in the MCU, but given how the character's already off to a great start in Spider-Man: Into The Spider-Verse, I went with Spider-Gwen instead. Fans love her, she has a cool suit and, let's face it, Gwen Stacy needs some redemption after her death in The Amazing Spider-Man 2. As I said, there's a lot of worthy candidates from the Spider-Verse corner of Marvel, so if you're not down with Spider-Gwen, just pretend I said your favorite pick here.
Magnus is the result of a child between Magneto and Rogue in another world, and if it sounds like a mutant with a combination of those abilities would be badass, you're absolutely correct. Magnus has the awesome powers of magnetism, to the point he could construct things like credit cards and Cerebro units using metal particles pulled from the air. One downside is that every other living thing he touches with his skin turns it into solid metal, which can make finding love and general companionship a challenge. While the Rogue powers aren't ideal, he does get that cool white stripe in his hair, which definitely adds to the cool factor.
As far as 'out there' Marvel characters go, Singularity is certainly one of the coolest. She has a pocket dimension inside of her body, can travel through time, teleport and track people telepathically. She'd be a great character who could merge characters of different realities together for a team-up adventure and then dump them back at their respective home universe with as little damage done to multiple continuities as possible. If Marvel Studios does commit to multiple legacy characters across different universes, Singularity would be great to have along for the ride for these reasons.
Reed Richards is one of the most brilliant thinkers in the Marvel universe and one of the most durable thanks to his unique DNA structure. This version of Reed Richards from Earth-1610 started out as a formidable hero, but is now an even more formidable villain. The Maker has existed as an antagonist across several universes during his run, thanks in part to a deal with Molecule Man that placed a version of himself across every universe. I would love to see Marvel introduce an alternate version of a hero in a villainous role, and this seems to be one of the best options for doing so.
Old Man Logan
Without a doubt, Old Man Logan is one of the more memorable alternate universe characters in the Marvel mythology. This Wolverine exists in a world in which almost all superheroes are extinct, and the nation is controlled in territories by prominent villains. I'll say that the story behind the character isn't so important to me, at least as much as the idea that this could be a roundabout way for Marvel to eventually bring back Hugh Jackman (or some other veteran actor) as Wolverine years from now. Of course, I still want a new Wolverine, but who doesn't want Jackman back as a slightly different Old Man Logan who didn't die?
The Hulk with Bruce Banner's intelligence is scary enough, but imagine that same Hulk but without his sanity and a good chunk of his hair. It's a scary combination and a reality Marvel heroes have faced as Banner has taken on the persona of "Maestro" in future timelines. Maestro is not the greatest dude; as one of those more tyrannical types, he believes that fixing the world in their vision is the best course regardless of what it took to get there. He's also one of the strongest versions of the character, which means he's a real pain in the ass to stop if one can even get the chance.
Dark Beast was created out of an alternate reality in which "Henry" McCoy studied under Mister Sinister and had a knack for experimentation on mutants in order to make them stronger. He did this through excessively torturous methods and genetic manipulation, which gained him his nickname as Beast. McCoy also experimented on himself, and as can be seen above, ended up changing his fur black rather than blue. He's not the most powerful hero-turned-villain on this list, but damn, he might be the most evil, I would imagine.
Gah Lak Tus
Marvel fans may be familiar with Galactus, and he's scary enough. I mean, ok, in a fictional universe, a giant being that travels the galaxy and randomly eats worlds is goofy as hell, which may be why the Ulitmate Marvel universe made the character a bit more disturbing in that reality. Gah Lak Tus is a being composed of a bunch of drones that look like Galactus and go beyond the simple act of world-eating. This Borg-like collective sends out psychic fear waves to the planets they attack and releases a flesh-eating virus that ravages the planet. It's awful, but also awesome, and I'd almost like to see this Galactus more than the OG one.
All of these characters would be great to see in the MCU one day, but we still have yet to see how the multiverse will factor into the franchise as a whole. Speaking of the multiverse, there's been some indication of how it could come about in an upcoming Marvel movie, though this latest speculation is only based on some cryptic leak.