Mary Rose Byrne (born 24 July 1979) is an Australian actress. She made her screen debut in the film Dallas Doll (1994), and continued to act in Australian film and television throughout the 1990s. She gained her first leading film role in The Goddess of 1967 (2000), which earned her the Volpi Cup for Best Actress, and made the transition to American cinema with a small role in Star Wars: Episode II – Attack of the Clones (2002), followed by Troy (2004), 28 Weeks Later (2007), and Knowing (2009).
Roles in Get Him to the Greek (2010), Bridesmaids (2011), Neighbors (2014), Spy (2015), and Instant Family (2018) established her as a comedic actress. She also starred in the horror film Insidious (2010) and its sequels Insidious: Chapter 2 (2013) and Insidious: The Red Door (2023); the superhero films X-Men: First Class (2011) and X-Men: Apocalypse (2016); and the family films Peter Rabbit (2018) and its sequel Peter Rabbit 2: The Runaway (2021). For her performance as a troubled mother in If I Had Legs I'd Kick You (2025), she received the Silver Bear for Best Leading Performance.
On television, Byrne appeared as Ellen Parsons in the legal thriller series Damages (2007–2012), which earned her nominations for two Golden Globe Awards and two Primetime Emmy Awards. She also portrayed Gloria Steinem in the miniseries Mrs. America (2020) and led the comedy series Physical (2021–2023) and Platonic (2023).