Evangeline Lilly is once again preparing to play the superhero Hope Van Dyne in Marvel Studios' upcoming movie Ant-Man and the Wasp: Quantumania. But, in addition to recently sharing the beginning stages of her "Wasp Workout" on social media, the actress may have also inadvertently let slip a major spoiler for the film.

Lilly recently posted a photo of the front page of the script for Quantumania to her Instagram page, and tagged a number of her co-stars. These includes actors who we already knew were slated to appear, such as franchise mainstays Paul Rudd, Michael Douglas and Michelle Pfeiffer. She also included newcomers like Kathryn Newton, who will portray the grown-up version of Ant-Man's daughter Cassie following that five-year time jump in Endgame, and Lovecraft Country star Jonathan Majors as the villain Kang the Conqueror.

But one name stood out to eagle-eyed MCU fans: Corey Stoll.

Stoll previously portrayed Darren Cross in the first Ant-Man movie back in 2015. He was that movie's antagonist, and used stolen Pym particles to create his own Ant-Man-esque suit, becoming the supervillain Yellowjacket. He vanished at the end of the film and has not been seen in the MCU since.

Lilly has since deleted the Instagram post, lending credence to the theory that Stoll will definitely be returning as Yellowjacket in some capacity.

It certainly wouldn't be the first time that Marvel Studios have brought back a recurring bad guy—Loki is about to embark on his own solo adventure series on Disney+, despite having died several times on-screen—but it remains to be seen whether Yellowjacket will play a central role in the movie, or appear as more of an Easter egg.

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