When it came to casting the new Supergirl, DC Studios exec James Gunn went above and beyond before honing in on Milly Alcock to star in the upcoming film “Supergirl: Woman of Tomorrow.”

Sources say Gunn and co-CEO Peter Safran flew multiple actors, including Meg Donnelly, to Atlanta for old-fashioned, onscreen auditions on the “Superman: Legacy” set. The actors also donned the Supergirl suit and boots, which is an atypical move in the superhero audition process (though Jamie Dornan once wore a makeshift Superman costume to his ill-fated audition for 2013’s “Man of Steel”).

Gunn first sparked to Alcock when he saw her playing Rhaenyra Targaryen in HBO’s “House of the Dragon.” But Donnelly made it a close contest and had the advantage of having voiced the role of Kara Zor-El/Supergirl in several Warner Bros. Home Entertainment’s animated films, including last year’s “Legion of Super-Heroes.”

Ultimately, Gunn was looking to move away from previous depictions of the Girl of Steel, particularly the long-running CBS/CW series fronted by Melissa Benoist, and is aiming for a less earnest and more edgy version of the iconic superheroine. In the new iteration, Supergirl travels across the galaxy to celebrate her 21st birthday with Krypto the Superdog. Along the way, she meets a young woman named Ruthye and winds up on a murderous quest for revenge.

Gunn himself weighed in on the matter on Threads on Tuesday, saying, “Milly was the FIRST person I brought up to Peter for this role, well over a year ago, when I had only read the comics. I was watching ‘House of the Dragon’ and thought she might have the edge, grace and authenticity we needed.”

The project has endured many false starts. Around the same time that the nearly finished “Batgirl” film was shelved as a tax write-off following the Warner Media-Discovery merger, the studio also quietly killed a Supergirl movie in the development stage. Sasha Calle, who plays the caped cousin of Kal-El, was introduced in the last year’s “The Flash” movie and was poised to get a spinoff of the Ezra Miller-led tentpole.

After Gunn and Safran took the DC reins in 2022, they started from scratch on Supergirl. Ana Nogueira (“The Vampire Diaries”) is writing the screenplay, while DC looks to attach a director in the coming weeks.