Who is Mighty Thor? Why is it Jane Foster?

The Marvel Cinematic Universe ushers in its next chapter with the arrival of Thor: Love and Thunder hitting theaters on July 8. The fourth film in the Thor franchise sees the return of Chris Hemsworth in the titular role, as well as the return of new fan-favorite characters such as Tessa Thompson’s Valkyrie and Korg, portrayed by director and writer Taika Waititi. The next installment of the MCU will also be significant as it will include not only one but two Gods of Thunder on the big screen.

Back when Love and Thunder was announced at San Diego Comic-Con in 2019, director Taika Waititi announced that Natalie Portman would make her return as Jane Foster in the fourth Thor film. Portman had previously portrayed the character in the first two films of the franchise: Thor and Thor: The Dark World. Portman’s return to the MCU would also come with a new title, as it was revealed her character would mark the first live-action appearance of Mighty Thor.

Mighty Thor is not a Thor “variant” or a Thor from another universe but is rooted in an original comics storyline. After Nick Fury whispers something to Thor which renders him unworthy to wield Mjolnir it opens the opportunity for another to wield the weapon and thus possess the power of the God of Thunder.

In this storyline, Jane Foster, who is simultaneously battling breast cancer, steps in to defend Asgard as the Norse home has lost its defender. Interestingly enough, by stepping in to help defend Asgard makes her worthy to possess the mantle of “Mighty Thor,” however it renders her chemotherapy useless. It is this sacrifice in choosing to remain a hero at the cost of her health that deems her worthy.

It remains to be seen whether Marvel Studios will accurately adapt this storyline into the MCU or whether they will tweak certain elements of the story. To fans' knowledge, there has been no indication that the MCU’s Jane Foster is suffering a similar circumstance to the Jane Foster of the comics, who is battling breast cancer. However, one theory could shed some light on how they plan to adapt this story in Love and Thunder.

Portman’s Jane Foster possessed the Aether/Reality Stone back in Thor: Dark World, to the point where it required a trip to Asgard in order to rid her of its hold given the damage it would do to her. Even though the Aether was removed from her in the film, perhaps there are still underlying effects in the aftermath. This coupled with the fact that Hemsworth’s Thor seemingly wants to carve his own path and no longer be a hero, could set up a similar plot where Jane Foster attempts to fill the void left by Thor and in doing so makes her own sacrifice that deems her worthy of wielding Mjolnir, effectively becoming Mighty Thor.

The underlying question remains as to whether by the end of the film, will Thor or Mighty Thor be left standing? Hemsworth has been tight-lipped regarding his future in the MCU, and if he chooses to step away perhaps it comes via a sacrifice by Thor in Love and Thunder, setting up Mighty Thor to carry the mantle in the MCU going forward.