Milly Alcock is one of the fastest-rising stars in Hollywood, lighting up our screens with leading roles on HBO’s much-hypedGame of Thrones prequel, House of the Dragon, and Netflix’s intoxicating black comedy Sirens. She was also hand-picked to take up the titular role in the 2026 DC Universe blockbuster Supergirl.
Alcock is based in London and can be spotted nonchalantly sitting front-row at the hottest runway shows in Paris or collaborating with Miu Miu. But not long ago, the famous Australian child actor was washing dishes at a cafe in Sydney’s Marrickville while she was waiting for her acting career to take off.
Here’s a deep dive into Alcock’s origins and the must-see performances that led to her donning the cape of the world’s No. 1 female superhero.
Born on 11 April, 2000, Amelia May Alcock was raised in the inner west Sydney suburb of Petersham. In a 2023 interview with Harper’s Bazaar, she describes her family as decidedly non-arty. “The arts felt like something that was just mine, that I had ownership over,” she said.
She was just 6 years old when she found her calling, feeling “like an utter rock star” as she starred in her local church’s production of Little Red Rocking Hood (a jazzed-up take on the fairytale classic), a feeling she says she’s chased ever since.
A self-starter from the off, she enrolled herself into Newtown High School of the Performing Arts and passed the audition. The school’s high-achieving and famous alumni also include Yael Stone, Virginia Gay, and Catherine Laga'aia, the star of Disney’s live-action Moana.
She arrived at the prestigious high school to discover that many of her classmates already had agents. So she started cold-calling agencies seeking a child acting agent – and landed one. “When I was 13, [I] called the agency, like, ‘Hi, can I have an audition?’,” she told the Standard. “I learned very young that no one’s going to do it for me.”
She started booking small jobs with brands such as Cadbury, KFC and Woolworths, joining the leagues of famous Australian actors who got their start in commercials. Alcock’s official television debut came in 2014, in a single-episode appearance on Network Ten’s romantic drama series Wonderland.
Between 2015 and 2017 she had a stint as one of the faces of the Disney Channel in Australia, presenting on the short-form series B.F. Chefs and Hanging With. She also appeared in a number of Australian television dramas, including Janet King, Fighting Season, A Place to Call Home, Les Norton, and the Netflix-produced Pine Gap.
In 2018, at age 18, Alcock dropped out of school to pursue what she considers her first big break – starring opposite Tim Minchin in Upright.
Upright
A big contributor to Alcock earning the Casting Guild of Australia Rising Star Award in 2018 was her performance as Meg, a teenage runaway who gets roped into helping struggling musician Lucky (played by one of Australia’s best musical theatre writers and biggest entertainment exports, Tim Minchin) transport an upright piano across the Outback to his ailing mother, in this critically acclaimed Foxtel comedy series.
“Working with Tim gave me a very clear understanding that when you’re on set, you’re there to do a job,” Alcock told Harper’s Bazaar. “You need to serve the story and speak up when you have an idea. Don’t be scared. I think he taught me to trust myself in a way that I’ve taken into every role since.”
Almost four years later, in late 2021, Alcock returned to Australia from wrapping on House of the Dragon to film Upright’s long-awaited second season.
The School
Alcock made her feature film debut in this Aussie indie horror, which also stars Will McDonald (who plays Cash on the Netflix hit Heartbreak High). Released in 2018, The School follows an ambitious doctor who awakens in an abandoned school where she must face all manner of horrors in a quest to find her missing son.
Around this time, Alcock also played supporting roles in Aussie crime thriller series Reckoning and the Stan Original supernatural thriller series The Gloaming.
House of the Dragon
Alcock gained international attention with her starring role in HBO’s massive Game of Thrones prequel series, House of the Dragon. Holding her own opposite veteran stars such as Matt Smith (The Crown, Doctor Who) and Paddy Considine, Alcock played young Princess Rhaenyra Targaryen. (An older version of the character was later played by English actor Emma D’Arcy.)
Major productions like this typically involve a rather demanding audition process, but – perhaps in part because casting was happening during the pandemic-scrambled days of 2020 – Alcock managed to land the role with two self-tapes for “an unknown project.”
Sworn to secrecy, Alcock kept showing up to her part-time job in a Marrickville cafe right up until she left to start filming in early 2021. “I was literally washing dishes every day,” she told Harper’s Bazaar. “Nobody knew!”
The Crucible
In 2023, Alcock made her mainstage theatre debut on London’s West End, playing the leading role of Abigail Williams in the National Theatre’s acclaimed production of The Crucible, Arthur Miller’s gripping parable of power and its abuse set during the Salem witch trials.
One review from Collider described her performance as “mesmerizing,” saying “Alcock fully portrays the nuances of Abigail’s character, moving her beyond the fickle and foolish girl she is often reduced to.”
Sirens
In 2025, Alcock starred alongside Julianne Moore, Kevin Bacon, and Meghann Fahy in Netflix’s sexy dark comedy miniseries Sirens, which deals in themes of class, family conflict, and high-stakes seduction. Both the series and Alcock’s performance as Simone – the live-in PA and pseudo–best friend to a wealthy socialite with a cult-like influence – earned strong reviews from critics, with the Guardian describing it as “utterly addictive” and “preposterously fun.”
Superman
In the lead-up to her major role as Supergirl (aka Superman’s cousin, Kara Zor-El), Alcock made a brief, uncredited appearance as the character in the final moments of James Gunn’s 2025 Superman starring David Corenswet, teasing what was to come.
Having joined the Superman set for just a single day – to “play-wrestle with a 4-foot-8 woman in a gray suit and mocap dots on her face in place of Kara’s unruly canine Krypto” – she made what GQ Magazine describes as “a lightning-bolt first impression.”
Supergirl
Set for release in June 2026, Supergirl has transformed Alcock into the latest superhero star of the DC Universe. Falling in step with the optimistic and heartfelt tone of 2025’s Superman, the film follows Kara Zor-El (aka Supergirl) as she celebrates her 23rd birthday by traveling across the galaxy with her dog Krypto. Her thrill-seeking trip, however, takes a dark turn into a murderous quest for revenge.
Alcock’s unfiltered honesty and “embarrassing admissions” during the press campaign leading up to the film’s release have sparked a lot of discourse, ranging from praise for her refreshing sincerity to misogyny-laced criticisms from die-hard comic book fans. As a recent profile in GQ Magazine put it, however, “Alcock displays an endearing, no-fucks-given attitude that, on paper, makes her an ideal fit for this rebellious iteration of Supergirl.”
