Natalie Portman is reprising her role as Jane Foster in Thor: Love and Thunder, which will also see her become the female Thor, who is officially known as the Mighty Thor. While this will be a new development in the MCU, Jane Foster had already taken on the role of Thor in Marvel Comics, though she has since become the new Valkyrie. However, the first time Jane ever lifted Mjolnir happened in the pages of Marvel's What If, which was a comic that dealt with stories set in other realities that were different from the main Marvel continuity.
The first time that Jane Foster became Thor happened in What If #10, which released way back in 1977. In the main Marvel continuity, Donald Blake discovered Mjolnir when he is trapped in a cave and, thus, became Thor, while in What If, it's Jane Foster who found the hammer in the cave. The writing on Mjolnir still says, "Whoever holds this hammer, if he shall be worthy, shall possess the power of Thor", but it has been established in other stories that gender doesn't matter to the wielder of Mjolnir, as characters like Rogue and Wonder Woman have lifted it in the past.
While she was recently named Mighty Thor, in this particular comic, Jane Foster took on the name Thordis, and she saved Donald Blake's life. Thordis used her powers to become a superhero and she quickly ran afoul of Loki, who had escaped from his imprisonment within a tree. Loki reported to Odin about the new incarnation of his son, and so, Thordis was called to Asgard, where most of the Norse gods couldn't help but be taken in by her beauty. Thordis was banished from Asgard and Sif was left in despair, as she had always hoped to wed Thor. Sif's sadness at not being able to marry the female Thor is interesting in hindsight, as Valkyrie will be the MCU's first LGBTQ hero, and she'll be searching for a queen in Thor: Love and Thunder.
After being banished from Asgard, Thordis returned to Earth and filled the same role as her male Thor counterpart, where she became a member of the Avengers. Sif followed her and seduced Donald Blake, who slowly became aware of his connection to Thor. Loki attempted to overthrow Asgard while Odin slept, which prompted Donald Blake, Sif, and Thor to travel across dimensions in order to stop him.
Odin stripped Thordis of her powers and returned Mjolnir to Thor, so that he could reclaim his memories and return to Sif's side. Jane Foster was rewarded for her valor by being turned into a goddess, yet the power was of little comfort, as she had lost the man she loved to another woman. It didn't take Odin long to make his move, as he waited a single panel to declare his intention to marry Jane Foster; they married one page later. Uatu the Watcher claimed that Odin shared all of the qualities that she admired in Donald Blake.
The return of Natalie Portman to the MCU came as a surprise to many fans, but it would be even more surprising if her love interest in Thor: Love and Thunder were played by Anthony Hopkins instead of Chris Hemsworth. Jane Foster's first stint as Thor showed her as being just as efficient as the male version of the character, but the bizarre manner in which she ends up with Odin at the end of the story is a distraction from what was an interesting (if bizarre) tale of the first female Thor. Perhaps Thor: Love and Thunder will do the character better justice.
