10 MCU Fan Theories That Just Won't Die
5. The X-Men Will Come From Another Universe
When the X-Men finally join the Marvel Cinematic Universe, there will be one huge question that needs answering before anything else can make sense. Where have they been? The MCU will be almost two decades old by then, possibly longer, so why haven’t mutants shown up since then?
Technically, there have been a couple of sightings in the past year. Bruno confirmed to Kamala Khan that she had a genetic mutation, and in She-Hulk’s second episode there was a tease about a man in a bar fight using metal claws. Outside of these two however, Earth-616 has seen no other mutants that we know of.
An almost built-in explanation would be if the mutants were brought to the main MCU universe from a different one, a universe where mutants and the X-Men had been long established. This would answer that question, and it would make sense as to why Professor X has so far only been seen on Earth-838.
One theory suggested that Thanos would bring them across from an alternate universe using the Reality Stone, but now that the multiverse concept has been blown wide open, there could be any number of ways the mutants jump from one universe to another. Even though mutants have technically been introduced on Earth-616 already, this is still the theory that many fans are sticking with.