‘This is going to change my life’: House Of The Dragon’s Milly Alcock set to fly again in Supergirl

SINGAPORE – Milly Alcock found out she was cast as Supergirl when the DC superhero movie’s co-producer James Gunn sent her a text message with a link to an article announcing she had landed the coveted role. That was in January 2024.

“I just got a text from you. No one called me to say, ‘You got the job.’ It was just a text with a link,” said the 25-year-old Australian actress. 

“I tried calling you, but you did not pick up your phone,” DC Studios’ co-chairman and co-chief executive Gunn, 59, protested. 

The American film-maker and Alcock were at a Dec 8 virtual press conference ahead of the launch of Supergirl’s teaser trailer on Dec 12. They were joined by Australian director Craig Gillespie, who helms the movie set to premiere on June 25, 2026.

Supergirl made a cameo at the end of Gunn’s Superman (2025), when she showed up at Superman’s abode, the Fortress of Solitude. She was introduced as the party-loving cousin of Kal-El, also known as Superman (David Corenswet) and the owner of Krypto the superdog. 

Alcock knew she was going to be Kara Zor-El, the Maiden of Might, after her screen test. 

“I just had an instinct... an intuition that I was like, I think this is going to change my life,” she said. “I was really excited. And then I was obviously scared. How am I going to pull this off?”

Based on American writer Tom King’s graphic novel Supergirl: World Of Tomorrow (2021 to 2022), the story paints Kara as a flawed superhero, someone who is the polar opposite of her famous cousin.

She meets an alien girl, Ruthye Marye Knoll (Eve Ridley), who is looking for justice for her father’s death at the hands of Krem of the Yellow Hills (Matthias Schoenaerts). 

From the trailer, it is evident that Gillespie’s take on Supergirl is more of a space adventure, a clear departure from Superman’s urban setting.

A lot is riding on relative newcomer Alcock to carry the second solo movie in the DC Universe.

But Gunn and Gillespie had nothing but faith in the young Sydney native after seeing her performance as the younger version of Princess Rhaenyra Targaryen in HBO’s Game Of Thrones spin-off series House Of The Dragon (2022 to present). 

Gunn wanted Alcock to be Supergirl from the get-go. “I knew that little girl from House Of The Dragon is the one,” he said. 

Gillespie, 58, added: “I’m so excited for everybody to see Milly in this. There can be a lot going on when you get these kinds of (superhero) films with big set pieces and action sequences. But every time I turn the camera on Milly, she just grounds it.”

He praised Alcock, who made her debut in a 2014 episode of Australian romcom series Wonderland, for bringing “humanity and vulnerability” to her character.

“You just can’t get enough of her humour and strength. It’s amazing,” said Gillespie, adding that he was very confident of Alcock’s range, having watched her past Australian TV works. 

Turning to his leading lady, the film-maker – known for Lars And The Real Girl (2007), I, Tonya (2017) and Cruella (2021) – gushed: “I’m really excited to introduce you to the world because this is going to be a very big platform. The character played so well to your strengths.”

To prepare for her role, Alcock was on set at 5.30am every day for 4½ months for physical training. “It became a habit,” she said. 

She also relied heavily on King’s book, which she called her “bible”.

“Kara was written so incredibly grounded and flawed, and like a person that we can all understand and empathise with,” said Alcock, who also starred alongside Julianne Moore and Meghann Fahy in the dark comedy miniseries Sirens (2025).

“Her strength is that she doesn’t hide behind her abilities. She may be a strong, powerful figure, but she is also a young woman navigating the galaxy.

“The fact that she’s a superhero is what makes her different. The superhero part is secondary. She’s a reluctant hero.”