King Arthur is a 2004 epic historical adventure film directed by Antoine Fuqua and written by David Franzoni. It features an ensemble cast with Clive Owen as the title character, Ioan Gruffudd as Lancelot and Keira Knightley as Guinevere, along with Mads Mikkelsen, Joel Edgerton, Hugh Dancy, Ray Winstone, Ray Stevenson, Stephen Dillane, Stellan Skarsgård and Til Schweiger.

The film is unusual in reinterpreting Arthur as a Roman officer rather than the typical medieval knight. Several literary works have also done so, including David Gemmell's Ghost King, Jack Whyte's Camulod Chronicles, and perhaps the strongest influence on this film, Bernard Cornwell's Warlord series. The producers of the film attempted to market it as a more historically accurate version of the Arthurian legends, supposedly inspired by new archaeological findings. The film also replaces the sword in the stone story with a darker and more tragic backstory of how Arthur claimed his sword Excalibur. The film was shot in Ireland, England, and Wales.

King Arthur was released by Buena Vista Pictures on July 7, 2004. The film received mixed to negative reviews with critics criticizing the setting, violence and battle sequences while praising the musical score, directing, performances and cinematography and grossed $203.6 million against a production budget of $120 million.