Inga Ibsdotter Lilleaas (born 9 April 1989) is a Norwegian actress. She gained widespread critical acclaim in 2025 for her role as Agnes Borg Pettersen in Joachim Trier's Sentimental Value. Her performance earned her the National Board of Review Award for Best Supporting Actress in addition to nominations for the Golden Globe and Academy Award for Best Supporting Actress.
Inga Ibsdotter Lilleaas was raised in Gol Municipality, Norway. Her parents ran a company that rented out costumes and equipment to amateur stage productions. As a high school student, she lived as a foreign exchange student in Brazil, where she learned to speak Portuguese. She studied theatre at Nord University, learning the Jacques Lecoq acting method focusing on physical theatre. She also spent a semester studying at the Lee Strasberg Theatre and Film Institute in New York City.
Lilleaas was nominated for the Amanda Award for Best Actress in 2015 for her film debut in Women in Oversized Men's Shirts (Kvinner i for store herreskjorter). In 2019, she performed the role of Hermia in A Midsummer Night's Dream at the Haugesund Theater in Haugesund, Norway. In 2021, she performed the role of Madame de Tourvel in Les Liaisons dangereuses. In 2023, she performed the role of Tamora in Titus Andronicus at the Nordland Theatre in Mo i Rana.
In 2023, she starred in the Netflix musical film A Beautiful Life. In 2025, she starred as Agnes Borg in Joachim Trier's Sentimental Value, which premiered at the Cannes Film Festival, for which she won the National Board of Review Award for Best Supporting Actress.
She is married to actor Gunnar Eiriksson, with whom she has one son.