Invincible creator Robert Kirkman knows who Steven Yeun is playing in the Avatar: The Last Airbender sequel movie, but doesn’t want to “lose any more sleep” after accidentally spoiling Thunderbolts: "I wish I didn't know"

Invincible creator Robert Kirkman is done spoiling news about his friend and colleague Steven Yeun, having learned his lesson with that accidental Thunderbolts leak.

"I don't want to lose any more sleep spoiling Steven Yeun news!" Kirkman told IGN, with a joking exasperation. "I cannot tell you how much that Thunderbolts thing affected me. Why would you guys bring that up? I'm so angry."

Back in 2023, it was announced that Steven Yeun would be joining the cast of Thunderbolts in an undisclosed role. Later that year, Kirkman accidentally let slip that Yeun called him during a costume fitting for none other than the Sentry, who wears a blue and yellow suit similar to Mark Grayson aka Invincible. "Guess I only do superheroes that are yellow and blue," he told Kirkman. At the time, Yeun's role still had not been revealed – and the exclusive, of course, spread like wildfire.

The following year, Yeun announced his departure from the film, citing scheduling conflicts. The role ultimately went to Lewis Pullman. In May 2025, Yeun joined the cast of the animated film The Legend of Aang: The Last Airbender, joining Dave Bautista in a mystery role. The film serves as a sequel to the original animated Nickelodeon show.

Continued Kirkman: "The best part is he told me who he's playing in The Last Airbender and I was like, 'I wish I didn't know. I wish I didn't know.'"

The Legend of Aang: The Last Airbender hits theaters on October 9, 2026. Invincible season 4 is set to hit Prime Video sometime in 2026. For more, check out our list of the most exciting upcoming movies in 2025 and beyond, or, check out our list of the best Prime Video shows to add to your streaming queue.