Part of Stranger Things featuring Millie Bobby Brown, Finn Wolfhard, Winona Ryder, David Harbour, and Gaten Matarazzo.
Rise to Fame
Billy Hargrove was supposed to be a one-note bully. Montgomery made him genuinely hard to look away from. He'd already booked the 2017 Power Rangers reboot, but that film didn't produce a sequel. Stranger Things did the real work. By season 3, Billy had a genuinely complicated arc and the SAG ensemble nominations followed. The breakout came from playing the villain nobody expected to root for.
In the Spotlight
At the peak of his Stranger Things fame, he walked away from Hollywood for three years. He's said the industry kept pushing him toward commercial projects and he wanted arthouse work instead. He came back with Went Up the Hill, an indie that premiered at Toronto in 2024 opposite Vicky Krieps, and followed it with Dead Man's Wire, a Gus Van Sant crime thriller opposite Bill Skarsgard. That's not the resume of someone who panicked about visibility. It's the resume of someone who waited.
Side Notes
Both his parents worked in the Australian screen industry, which means he grew up knowing it as a business, not a dream. He compiled Beat poetry into a podcast called DKMH in 2019 (over 800,000 plays, later published as a book) while still in the middle of his biggest role. The Engagement Party will be his directorial debut. He's not waiting for his acting career to plateau before building the next thing.