Milly Alcock’s Supergirl casting hopes could be dashed by James Gunn’s secret plans for a DC multiverse

David Corenswet’s Superman is not the only DCU hero who’s about to fly up, up, and away into cinemas soon enough, as his on-screen cousin Supergirl looks to be cast any day now.

Supergirl: Woman of Tomorrow, a follow-up to July 2025’s Superman: Legacy, is on the cusp of casting its leading lady. And, according to the internet, it’s a one-horse race. Deadline reports that Emilia Jones, Meg Donnelly, and Milly Alcock are the top three actresses in the running to play Kara Zor-El, a character only just portrayed by Sasha Calle in The Flash in 2023. While it remains to be seen who Gunn and DC Studios will hire, Alcock’s legion of fans from her winning portrayal of Young Rhaenyra on HBO’s House of the Dragon know who they’re voting for.

And yet the significance of one of Alcock’s competitors for the coveted Kryptonian gig might just hint at the real reason that the 23-year-old Australian star isn’t as much of a shoe-in as you might think.

Supergirl: Woman of Tomorrow contender is already playing Supergirl

While CODA veteran Jones is perhaps the outlier of these three — although she shouldn’t be discounted — DC fans may be intrigued to hear that Donnelly is within an arm’s distance of become the DCU’s Supergirl. The fact is that Donnelly is already playing Supergirl. The former Disney Channel star — most known for the ZOMBIES movies — voices the Girl of Steel in Warner Bros. Animation’s DC animated movies.

Donnelly debuted as the heroine in Justice League: Crisis on Infinite Earths – Part One, which released on digital this Jan. 9 and arrives on disc from Jan. 23, and will reprise the role in the upcoming Part Two. What’s interesting is that these films are an adaptation of the quintessential comic book multiverse story, the one that started them all. While Gunn is unlikely to offer a live-action adaptation anytime soon, due to the DCU just getting started, the fact Donnelly is on his Supergirl shortlist may indicate he’s already intending to create ties with the wider DC multiverse.

Obviously, Gunn will be looking for the best person for the part of Supergirl period, but hiring Donnelly would immediately generate a through-line between other iterations of the DC mythos and his own. Not only does this lay the groundwork for a DCU multiverse later on — something that’s important in order to catch up to Marvel — but it would also allow for the DCU to waste no time honoring the legacy of DC’s rich and multifaceted history. Hmm, legacy, where have we heard that word before…?

Of course, the opposite may be true, and Donnelly’s prior connection with the character could cause Gunn and his team to lean the other way, in an attempt to make sure they’re delivering a Supergirl we’ve never seen before. The role is all still to play for, then, and it could well go to Alcock, but there’s a strong chance that our next Woman of Tomorrow might’ve been cast yesterday.