6 times Marvel has subtly reintroduced mutants to the MCU

Alright, so Scarlet Witch (Elizabeth Olsen) and Quicksilver (Aaron Taylor-Johnson) aren't exactly a subtle introduction into the Marvel Cinematic Universe since they're main characters in "Avengers: Age of Ultron."

But general audiences might not know that they're mutants in the Marvel comics and have both been part of key "X-Men" stories as well as "Avengers."

In fact, their father is the iconic villain-turned-hero, Magneto, so they're very important to the overall mythos of the X-Men.

Scarlet Witch and Quicksilver arrived at a time when Marvel Studios didn't have the screen rights to all the X-Men characters, and so weren't referred to as mutants.

Their powers in the MCU come from the Mind Stone, after being experimented on by the villainous folks over at Hydra. But it wouldn't take much for the movies to just explain that the experiments unlocked the mutant gene in their bodies.

This is all without mentioning the ultra-meta cameo in "WandaVision" from Evan Peters, who played Quicksilver in Fox's "X-Men" prequel movies.

The star isn't playing the same version of the character because Wanda Maximoff is rewriting reality as she sees fit (he's really a man called Ralph Bohner) but it's an excellent cameo.

When "Ms. Marvel" arrived on Disney+, most fans were expecting the young hero to get an origin story that was similar to that of the Marvel comics, in which she's actually something called an Inhuman.

Inhumans are descendants of people who were experimented on by an alien race called the Kree, and when they come into contact with a substance called the Terrigen Mist, they develop superpowers.

However, Kamala Khan (Iman Vellani) develops her abilities when she straps on a mystical bangle that belonged to her grandmother for the first time.

By the end of the series, it's revealed by Bruno Carrelli (Matt Lintz) that Kamala's fancy new accessory isn't what lets her access her powers, it's actually down to a "mutation" in her genetic makeup.

That reveal is subtly soundtracked by a few notes of the classic "X-Men" theme song from the 1992 animated series.

It's a subtle way of readjusting Ms. Marvel's powers for the modern MCU, as well as getting fans excited for more mutant madness further down the line.

In "She-Hulk" episode two, Jennifer Walters (Tatiana Maslany) is on a job hunt after being fired from her previous role due to her newfound transformation.

But when she's looking online, there's a web page full of random news articles and details pertaining to the wider MCU.

Some of them are more obvious, like an advert for the "Iron Man Threes" sneakers, but there's one headline that will be instantly recognizable for anyone remotely familiar with Marvel movies from the last two decades.

The headline reads, "Man fights with metal claws in bar brawl," which can only be a reference to Logan Howlett himself: Wolverine. Bar brawling is definitely something the hero would do, and he never really has any qualms about popping his claws out to make a point.

For now, it's not clear whether the X-Men have formed in the MCU or not, but regardless, Wolverine is seemingly already out there kicking butt.

"She-Hulk" is crammed with references and details you missed that refer to the wider MCU, and it even managed to bring Daredevil (Charlie Cox) back in a big way. But the show dumped a ton of mutant hints in the end credits of episode five.

A huge part of the story sees Nikki (Ginger Gonzaga) try to get Jen in with a tailor to make her clothes that would fit her in She-Hulk form.

Pug (Josh Segarra) helps Nikki in exchange for help nabbing himself an extra pair of the Iron Man Threes sneakers. Although the episode doesn't show off the superhero-inspired kicks in live action, the illustrated credits sequence shows Pug and Nikki surrounded by many pairs of sneakers, which are all inspired by various costumed crusaders.

The shelves are filled with references to Cyclops, Deadpool, Wolverine, Namor the Submariner, Cable, Bishop, and Juggernaut, who are all mutants in the comics.

Obviously, it's a tongue-in-cheek detail that's meant just for fans, rather than an actual reference to characters who are in the MCU right now.

How would a sneaker company even know about Namor? "She-Hulk" takes place before "Black Panther: Wakanda Forever," and the guy lives underwater!

But still, it's an acknowledgment that they're out there. And speaking of Namor…

Way before the Avengers first assembled and Thanos (Josh Brolin) was teased as the MCU's first big bad, Kevin Feige was cleverly sowing seeds for future characters to show up further down the line.

Yes, "Iron Man 2" featured a few nods to upcoming films at the time, like "Captain America: The First Avenger," and "Thor," but it seems Nick Fury (Samuel L. Jackson) had already tracked down Namor's home.

The end of the 2010 film sees Fury speak to Tony Stark (Robert Downey Jr.) about the Avengers Initiative, and a world map can be seen in the background with several highlighted locations.

One of the locations is very clearly Wakanda in Africa, and there's another location off the coast in the Atlantic Ocean, where Namor's home in the comics, Atlantis, is typically found.

Namor is a mutant in the comics, and his retconned origin story actually makes him the very first mutant to arrive in Marvel's long history because he first debuted back in 1939's "Marvel Comics" #1.

And last, but definitely not least, is the return of Professor X (Patrick Stewart) himself.

Yes, the iconic leader of the X-Men shows up in "Doctor Strange in the Multiverse of Madness" as part of the Illuminati on Earth-838.

The film doesn't acknowledge the fact that he's a mutant, although it does show him using his telekinetic abilities to reach into Wanda Maximoff's (Elizabeth Olsen) mind.

Of course, the film also uses the theme music from the 1992 "X-Men" animated series as he arrives in the room in a yellow wheelchair.

It's obviously a different version of the hero to the one audiences know and love from the "X-Men" movies of the early 2000s and beyond, but it at least confirms that mutants exist across the multiverse.

So, it's only a matter of time before they properly show up in the MCU.