The Great Yokai War (Japanese: 妖怪大戦争, Hepburn: Yōkai Daisensō) is a 2005 Japanese fantasy film directed by Takashi Miike, produced by Kadokawa Pictures and distributed by Shochiku. The film stars Ryunosuke Kamiki, Hiroyuki Miyasako, Chiaki Kuriyama, and Mai Takahashi.

The film focuses largely on creatures from Japanese mythology known as yōkai (妖怪, variously translated as "apparition", "goblin", "ghoul", "spirit", or "monster"), which came to prominence during the Edo period with the works of Toriyama Sekien. It also draws inspiration from Aramata Hiroshi's Teito Monogatari, with the novel's antagonist Katō Yasunori appearing as the main antagonist in the film.

The film is considered a loose remake of the 1968 Daiei film Yokai Monsters: Spook Warfare, but also draws influence from Shigeru Mizuki's GeGeGe no Kitarō manga series of the same name. Additionally, Daiei Film's iconic tokusatsu characters Gamera and Daimajin that have influenced productions of the company's yokai films including Yokai Monsters, were also briefly mentioned both in the film and the novelization of the 2005 film.

All three are retellings of the famous Japanese tale of Momotarō, which features the title character driving a group of demons away from Kikaigashima with the help of native animals. While these previous adaptations have been read mostly as nationalist narratives, with the native yōkai driving out invading forces, The Great Yōkai War has been read instead for the clash between Japan's traditional landscape and its modern culture. This is largely due to the film's use of kikai (機械, lit. "machine monsters"), created by Katō fusing the yōkai with machines, and the absence of invading Western or otherwise foreign forces.

Mizuki, whose work is considered an important part of yōkai discourse and culture due to his contributions in pop culture and academic study, acted as an advisor for the film and even made an appearance as the Great Elder Yōkai. The cameo is not only a nod to Mizuki's status as a yōkai expert, but his closing words also resonate closely with the theme of his manga of the same name. Similarly, his role as a peace-keeper is one referenced throughout his work, and is born of his own experiences from real war.

The Great Yokai War was theatrically released in Japan on August 6, 2005, and grossed ¥2 billion. In 2006, the film was released internationally by Tokyo Shock. A sequel, was released in Japan on August 13, 2021.