Is Milly Alcock’s Supergirl in James Gunn’s Superman?

House of the Dragon‘s Milly Alcock is officially DC Studios’ new Supergirl – does this mean she’s in James Gunn’s Superman reboot? And what about her predecessor, The Flash star Sasha Calle?

Is Milly Alcock’s Supergirl in the Superman Reboot?

Maybe. There are conflicting reports on whether Milly Alcock will debut as Kara Zor-El/Supergirl in Superman. The Wrap confirmed that Alcock is attached to the production in January 2024, however, Deadline‘s sources later claimed that’s “not 100%.” That said, the consensus among the industry trades is that Alcock’s introduction as Supergirl will happen in a non-Supergirl-centric project.

What’s more, insiders remain convinced that said project is Superman. If true, it’s currently unclear how big a role Alcock’s Supergirl will play in the Superman reboot; she may have a fully-fledged supporting part, or she may only make a brief cameo. What we do know is that Alcock will then reprise the role in her own standalone blockbuster, Supergirl: Woman of Tomorrow. Due out in July 2026, this project takes its cues from Tom King and Bilquis Evely’s acclaimed comic book miniseries of the same name.

James Gunn addressed Alcock’s casting in an Instagram post shortly after it was announced. While the DC Studios co-chair and co-CEO didn’t shed any light on her potential involvement in Superman, he did explain why she ultimately landed the gig. “I first became aware of [Alcock] in House of the Dragon,” Gunn wrote. “But I was blown away by her varied auditions and screen tests for Supergirl. She embodies Kara as envisioned by Tom King, Bilquis Evely, and [screenwriter] Ana Nogueira.”

Related: Superman: Who Is Edi Gathegi’s Mister Terrific in James Gunn’s Reboot?

What About Sasha Calle’s Supergirl?

So, Milly Alcock’s Supergirl is (probably) in Superman, but what about Sasha Calle’s incarnation of the character? After all, Calle only recently suited up as the Maid of Might in 2023’s The Flash. Unfortunately for fans of this version of Supergirl, Calle’s crime-fighting days are over. When Gunn’s Superman finally drops, it’ll complete the transition from the DC Extended Universe canon to its replacement, the DC Universe. As part of this, several legacy actors will exit the franchise, including Calle. This wasn’t always the plan, though.

Related: Superman III’s Original Script Was Genuinely Bonkers

DC Studios reportedly had plans for Calle to portray Supergirl in additional movies, including a Flash sequel. However, after Warner Bros. installed Gunn and Peter Safran as joint studio heads, the pair scrapped The Flash 2 and several other follow-up films in favor of starting fresh. Calle nevertheless met with Gunn and Safran about the possibility of playing Supergirl again and was optimistic about her chances. Yet the role ultimately went to Alcock, leaving Calle sidelined for both Superman and Supergirl: Woman of Tomorrow.

James Gunn’s Superman reboot streaks into cinemas on July 11, 2025.