Some casting news was released for Spider-Man: Brand New Day, and one of the most interesting additions might connect the film to the upcoming Disney+ MCU series Ironheart. The connection stems from the fallout of the Brand New Day comic book storyline in Amazing Spider-Man.
The casting news for Spider-Man 4 is that Stranger Things actress Sadie Sink signed on as a "sharp and free-spirited" character with a "mysterious past." Rumors that Sink is playing Mayday Parker, Peter Parker's daughter from somewhere in the Multiverse, play into the Ironheart casting rumors.
While The Hood is the main villain for Riri Williams's Ironheart, another major actor has been cast in a role many fans theorized is a major big bad. Borat's Sacha Baron Cohen signed on for the role. While his character identity hasn't been officially revealed, the biggest rumor is that he will finally bring Mephisto to the MCU after years of speculation. In Marvel Comics, Mephisto has a strong connection to Mayday Parker, and it all comes from the Brand New Day comic book storyline.
Ironheart’s three-episode premiere on Disney+ is June 24, 2025, while Spider-Man: Brand New Day will release in theaters on July 31, 2026. Ironheart features Dominique Thorne in the leading role alongside Anthony Ramos, Alden Ehrenreich, Lyric Ross, and more, while Spider-Man 4 brings veterans Tom Holland and Zendaya and newcomers Sadie Sink and Liza Colón-Zayas to the big screen.
Who Is Mayday Parker in Marvel Comics?
One of the bigger Spider-Man casting theories is that Sink will play Mayday Parker. This theory suggests she is the daughter of Tobey Maguire and Kirsten Dunst's Peter and Mary Jane Parker. Fans of Across the Spider-Verse have already seen Mayday as a toddler, the daughter of Peter B. Parker.
In Marvel Comics, Mayday Parker was introduced in an issue of What If...? in 1998. While this was supposed to be an alternate-world one-shot issue, fans loved the character, and Marvel brought her into the fold. Known as Spider-Girl, she was part of the M2 imprint, which included a possible future for the Marvel Universe, with kids of everyone from Spider-Man and Captain America to Juggernaut and Wolverine.
However, Marvel soon brought her into the real Marvel Universe thanks to the Spider-Verse crossover event. She then appeared in the Secret Wars comic book series, which should be interesting to anyone looking for what might happen in the future Avengers MCU movie. However, she also has a connection to Mephisto.
How Is Mephisto Connected to Mayday Parker in Spider-Man Comics?
The interesting thing about this rumor is that the movie is titled Brand New Day. It plays into the Dan Slott comic book storyline where Mephisto erases Peter Parker's marriage to Mary Jane Watson and separates them in exchange for saving Aunt May's life after being shot in the Civil War storyline.
It was one of the most controversial Spider-Man comic book storylines in history, with many fans rebelling at rebooting Peter Parker's life and eliminating his marriage to Mary Jane. While it seemed there was no reason for this other than just making fresh stories, a comic book story years later explained it all.
In 2018, Spider-Man battled a new villain known as Kindred in The Amazing Spider-Man comics. This villain was brought back from the dead to torment the Wall-Crawler, and his identity was kept a mystery for most of the story. However, Doctor Strange uncovered the truth in Amazing Spider-Man #74 (2018). Mephisto had something to do with this resurrection, continuing to make Peter's life a living hell for a previously unknown reason.
However, in this issue, Strange learned the truth. Mephisto had looked into the future to see his eventual fate. He would one day succeed in bringing Hell to Earth and rule over all. However, one person finally stopped him. Unexpectedly, it wasn't who he expected. While initially telling Strange it was Spider-Man, he finally told the truth. Mayday Parker, as Spider-Girl, is fated to end his reign of terror. He ended Peter and Mary Jane's marriage and created Brand New Day to ensure Mayday Parker was never born.
What This Means for Spider-Man: Brand New Day
Since the MCU has yet to confirm that Sacha Baron Cohen and Sadie Sink are playing Mephisto and Mayday Parker, everything right now is just rumors and speculation. However, Mayday Parker's inclusion in Spider-Man 4 could possibly link those two characters and hint at what might come in Avengers: Secret Wars.
In the comics, Spider-Girl was part of Secret Wars, and she is also someone that Mephisto fears above all others. As Peter Parker's daughter, who was never born in the mainline continuity, she also represents something that Peter could see in his future. If Mephisto is tied to Spider-Man in the MCU, the arrival of Mayday Parker could tie Ironheart on Disney+ with one of the MCU's most successful franchises in a big way.
