James Gunn Shoots Down a Weird DC Casting Theory

The new Supergirl is a familiar face.

LOS ANGELES, CALIFORNIA - JANUARY 15: Milly Alcock attends the 28th Annual Critics Choice Awards at ...
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Superman: Legacy has finally found its Supergirl. After a long casting process where fans were updated as the pool of candidates was whittled down, the DCU’s reboot movie officially has its Kara Zor-El. Notably, it’s an actor Warner Bros. Discovery has worked with before. Could this mean the DCU will continue to cast from other Warner Bros. franchises, or is it just a coincidence?

Deadline confirmed that Supergirl will officially be played by Milly Alcock, best known for playing young Rhaenyra Targaryen in House of the Dragon. Because the Game of Thrones spinoff has moved on to the character’s older version, Alcock is no longer committed to the series and can devote herself to a new project. The new DCU is about as big as it gets.

It’s not the first time Gunn has looked to a hit HBO series for casting: Anthony Carrigan, best known for his role in Barry, will also star in Superman: Legacy as Metamorpho. With all HBO stars apparently fair game for a DCU role, it’s fun to speculate about seeing Bella Ramsey, Kieran Culkin, or even Zendaya in a future casting announcement.

Superman: Legacy director and DC Studios co-chair James Gunn has thrown some cold water on such fan-casting, however. Gunn reposted the story on his Instagram, confirming the casting and reassuring fans Alcock didn’t earn the role purely through her previous Warner Bros. work. “Milly is a fantastically talented young actor, and I’m incredibly excited about her being a part of the DCU,” Gunn said. “Yes, I first became aware of her in House of the Dragon but I was blown away by her varied auditions and screen tests for Supergirl.”

Milly Alcock is jumping from the Game of Thrones universe to the DC Universe.


Being on HBO can quickly elevate an actor’s profile, but it’s a bit premature to suggest some sort of pipeline has been established. And while Alcock’s casting is (fitting for House of the Dragon) a little bit incestual, she won’t be playing the straightforward heroine you may expect. After being introduced in Superman: Legacy, she’ll have her own spotlight movie, Supergirl: Woman of Tomorrow. In January, Gunn told Variety what fans should expect from this version of Kara Zor-El..

“We see the difference between Superman, who was sent to Earth and raised by loving parents from the time he was an infant, versus Supergirl, who was raised on a rock chip off of Krypton, and watched everyone around her die and be killed in terrible ways for the first 14 years of her life,” he said.

If there’s one thing we know Alcock can do, it’s play a character trying to keep it together after a childhood full of high-stakes bloodshed. This time, she’ll just channel it in a supersuit instead of a fantasy gown.

Superman: Legacy hits theaters July 11, 2025.

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