DC Studios’ Supergirl arrives on HBO Max, giving Milly Alcock’s origin story a broader stage

When DC Studios chose Craig Gillespie to direct the second film in James Gunn’s reimagined DC Cinematic Universe, the mandate carried real weight: build an origin story that earns Kara Zor-El her own mythology, not as a footnote to her more famous cousin but as a universe-defining character in her own right. Milly Alcock — who broke through internationally in House of the Dragon, playing the young Rhaenyra Targaryen — spent years inhabiting a Supergirl who is headstrong, morally unresolved, and determined to do good entirely on her own terms. The film arrived in theaters in June to a complicated reception. Now it arrives somewhere wider.

The premise places Kara not as a hero in waiting but as an interplanetary nomad — displaced, tough, and not always likable. The story finds her reluctantly teaming with an unlikely companion after a ruthless adversary threatens those closest to her, including Krypto, her dog. What begins as a mission of vengeance steadily confronts a harder question: whether justice requires anything fundamentally different from revenge. Ana Nogueira’s screenplay holds those personal stakes at the center even as the scale expands to interstellar distances, and Gillespie — known for I, Tonya and Cruella — brings his familiar interest in protagonists who resist easy sympathy.

Alongside Alcock, the cast includes Matthias Schoenaerts, Eve Ridley, David Krumholtz, Emily Beecham, and Jason Momoa, with David Corenswet appearing as Clark Kent — establishing the connective tissue between Supergirl and Gunn’s earlier Superman. The film also launches a same-day ASL version on HBO Max, performed by Catalene Sacchetti and directed by Jonaz McMillan, continuing a push for parallel accessible releases that the broader streaming industry has been slow to adopt.

Milly Alcock as Kara Zor-El with her dog Krypto in a scene from the Supergirl film — Image: DC Studios / Warner Bros. Pictures

Supergirl makes its global streaming debut exclusively on HBO Max on Thursday, September 10. HBO’s linear broadcast follows on Saturday, September 12, at 8:00 p.m. ET. The film was produced by Peter Safran and James Gunn at DC Studios, with executive producers Nigel Gostelow, Chantal Nong Vo, and Lars P. Winther. The screenplay is by Ana Nogueira; the character is based on the DC original created by Jerry Siegel and Joe Shuster.

The streaming debut gives Supergirl — and Alcock’s performance at the core of it — a second window to reach the wider audience that the theatrical run didn’t. As Gunn’s DCU continues to build with further projects already in development, whether this chapter finds its footing on HBO Max may ultimately matter more to the franchise than the opening weekend numbers did.

Tags: hbo max, James Gunn, Milly Alcock, DC Studios, Craig Gillespie, Supergirl