Thor: The Dark World is a 2013 American superhero film based on the Marvel Comics character Thor, produced by Marvel Studios and distributed by Walt Disney Studios Motion Pictures. It is the sequel to 2011’s Thor and the eighth film in the Marvel Cinematic Universe (MCU). The film was directed by Alan Taylor, with a screenplay by Christopher Yost and the writing team of Christopher Markus and Stephen McFeely. It stars Chris Hemsworth as Thor, alongside Natalie Portman, Tom Hiddleston, Anthony Hopkins, Stellan Skarsgård, Idris Elba, Christopher Eccleston, Adewale Akinnuoye-Agbaje, Kat Dennings, Ray Stevenson, Zachary Levi, Tadanobu Asano, Jaimie Alexander, and Rene Russo. In Thor: The Dark World, Thor teams up with Loki to save the Nine Realms from the Dark Elves led by the vengeful Malekith, who intends to plunge the universe into darkness.

Development of Thor: The Dark World began in April 2011, when producer Kevin Feige announced plans for a sequel to follow the crossover film The Avengers. In July 2011, Kenneth Branagh, the director of Thor, withdrew from the project. Brian Kirk and Patty Jenkins were considered to direct the film before Taylor was hired in January 2012. The supporting cast filled out in August 2012, with the hiring of Eccleston and Akinnuoye-Agbaje. Principal photography began in September 2012 in Surrey, England with filming continuing in Iceland and London, before wrapping up in December 2012. Thor: The Dark World was converted to 3D in post-production.

Thor: The Dark World premiered at the Odeon Leicester Square in London on October 22, 2013, and was released on November 8, 2013, in the United States. Many critics praised it for its visual effects and performances (particularly Hemsworth and Hiddleston), but criticized its story, villain, and pacing; many critics declare it the weakest of the MCU films. The film was a commercial success, grossing over $644 million worldwide and making it the tenth highest-grossing film of 2013. A third film, Thor: Ragnarok, was released on November 3, 2017, and a fourth film, Thor: Love and Thunder, is in development and is scheduled for release on November 5, 2021.