Black Widow star, David Harbour, has hinted the film could introduce the Winter Guard, Russia's version of the Avengers. The MCU is gradually revealing that superhumans have always been part of its world, with Falcon & Winter Soldier introducing Isaiah Bradley, a Captain America who served during the Korean War. The evidence is building that Black Widow will play a key role in continuing these revisions to world history.

Official character profiles for Harbour's Red Guardian have confirmed his character is a super-soldier created during the Cold War to be Russia's answer to Captain America. This suggests that, in the MCU, the Cold War was a superhero arms race in which the Soviet Union and the U.S.A. competed to develop superhuman champions. This has naturally led to speculation that Black Widow could further flesh out the history of the MCU's Cold War, and even introduce other superhumans who served as part of it.

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Harbour has just added fuel to the fire in an Instagram post celebrating the upcoming release of Black Widow. In the comics, the Winter Guard are Russia's answer to the Avengers, and most of the characters he names in the caption of his post have all been associated with different incarnations of the team; Ursa Major, the two Black Widows, Crimson Dynamo, and Sputnik. Check out Harbour's post below:

The mention of Ursa Major is particularly interesting. In the comics, Ursa Major is a mutant who possesses the ability to morph into a giant bear; there's already been speculation Ursa Major could be in Black Widow, perhaps with Dutch strongman, Olivier Richters, playing the part. In a quirk of timing that may well be no coincidence, Hasbro recently confirmed one of their popular Marvel Legends action figure ranges will include an Ursa Major Build-A-Figure. If Ursa Major does indeed appear in Black Widow, then he would potentially be the MCU's first identifiable mutant. He may well not have been a Fox property, though, simply because he's commonly associated with the Avengers, not the X-Men; it's likely his rights were shared, in a similar manner to Quicksilver and the Scarlet Witch. Still, with mutants now being back with Marvel Studios, Marvel should be able to play Ursa Major straight.

Harbour's reference to "CD" is also exciting, because that's Crimson Dynamo - a classic Iron Man villain. In Iron Man 2, Tony Stark insisted it would be years before anybody managed to duplicate Iron Man technology, but it's possible that Russia had managed to do so by 2016 - and had created Crimson Dynamo. Marvel recently published a book called The Wakanda Files that revealed Russia possesses palladium, which powered Stark's original arc reactor, hinting that country may be able to create first-generation Iron Man armors. Black Widow could therefore be setting up the MCU's upcoming Armor Wars TV series on Disney+, with War Machine attempting to take down people who have duplicated and stolen Stark tech in the aftermath of Avengers: Endgame.

Harbour's comment is smart marketing, sure to make viewers very curious indeed about how Black Widow could affect the MCU going forward. As things stand, it's difficult to understand why Marvel considers this the right time for a Black Widow movie, given Scarlett Johansson's Natasha Romanoff sacrificed herself in Avengers: Endgame, forcing this to be something of a prequel. But if the film introduces the Winter Guard, then it adds some thrilling new concepts into the MCU, weaves them into the shared universe's rich history, and perhaps even introduces the MCU's first mutant to boot. Black Widow may be a lot more important than many think.

More: Every Upcoming Marvel Cinematic Universe Movie

Source: David Harbour