The Lord of the Rings: The War of the Rohirrim is an upcoming 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. Produced by New Line Cinema, Warner Bros. Animation, and Sola Entertainment in association with WingNut Films, it stars Brian Cox, Gaia Wise, Luke Pasqualino, and Miranda Otto. The War of the Rohirrim is set 183 years before Peter Jackson's The Lord of the Rings film trilogy (2001–2003) and tells the story of Helm Hammerhand (Cox), a legendary king of Rohan, and his family as they defend their kingdom against an army of Dunlendings.

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 film trilogy—and writers Addiss and Matthews. Gittins and Papageorgiou re-wrote the script, which is based on details in the appendices of Tolkien's The Lord of the Rings (1954–55) covering the history of Rohan's rulers. They chose to focus on Helm's unnamed daughter, whom they called Héra for the film. Sola Entertainment provided the traditional 2D animation, taking visual inspiration from Jackson's films. The main cast was revealed in June 2022, including Wise as Héra and Otto reprising her role as Éowyn from the film trilogy. Jackson and his film trilogy co-writer Fran Walsh were being credited as executive producers by June 2024.

The Lord of the Rings: The War of the Rohirrim is scheduled to be released theatrically in the United States on December 13, 2024, by Warner Bros. Pictures.