The Lord of the Rings: The War of the Rohirrim is a 2024 anime fantasy film directed by Kenji Kamiyama from a screenplay by Jeffrey Addiss & Will Matthews and Phoebe Gittins & Arty Papageorgiou, based on characters created by J. R. R. Tolkien. Set around 200 years before Peter Jackson's The Lord of the Rings (2001–2003) and The Hobbit (2012–2014) film trilogies, it tells the story of legendary Rohan king Helm Hammerhand. When the neighboring Dunlendings propose a marriage to his daughter Héra, Helm unintentionally kills their leader in a fistfight and starts a war. The film stars Brian Cox as Helm and Gaia Wise as Héra, alongside Luke Pasqualino, Laurence Ubong Williams, Lorraine Ashbourne, and Miranda Otto. Presented by New Line Cinema, it was produced by Warner Bros. Animation and Sola Entertainment in association with WingNut Films and Domain Entertainment.

The film was announced in June 2021 and development was fast-tracked to prevent New Line from losing the film adaptation rights for Tolkien's novels. Kamiyama was involved by then, as were producer Philippa Boyens—who co-wrote Jackson's films—and writers Addiss and Matthews. Gittins and Papageorgiou re-wrote the script, which is based on details in the appendices of Tolkien's novel The Lord of the Rings (1954–55) covering the history of Rohan's rulers. They chose to focus on Helm's daughter, who is unnamed in the appendices. Sola Entertainment provided the traditional 2D animation, taking visual inspiration from Jackson's films. The main cast was revealed in June 2022, including Miranda Otto, reprising her role from Jackson's trilogy as Éowyn, who narrates the film. Jackson and his trilogy co-writer Fran Walsh were being credited as executive producers by June 2024.

The Lord of the Rings: The War of the Rohirrim premiered on December 3, 2024. It was released theatrically by Warner Bros. Pictures in international markets from December 5 and in the United States on December 13. The film grossed $20 million worldwide on a $30 million budget and received mixed reviews from critics.