Sinister is a 2012 American supernatural horror film directed by Scott Derrickson, and written by C. Robert Cargill and Derrickson. It stars Ethan Hawke as a struggling true-crime writer whose discovery of snuff films depicting gruesome murders and strange supernatural elements in his new house puts his family in danger. Juliet Rylance, Fred Thompson, James Ransone, Clare Foley, Michael Hall D'Addario, and Vincent D'Onofrio appear in supporting roles.

Sinister was inspired by a nightmare Cargill had after watching the 2002 film The Ring. Principal photography on Sinister began in Autumn of 2011 on Long Island, New York with a production budget of $3 million. To add to the authenticity of old home movies and snuff films, the Super 8 segments were shot on actual Super 8 cameras and film stock. The film was a co-production between the United States, Canada, and the United Kingdom.

It premiered at the SXSW festival on March 10, 2012. It was released in the United Kingdom on October 5, 2012, and in the United States on October 12. Critics praised its acting, direction, cinematography and atmosphere, but criticised its use of jump scares and other horror clichés. It was a box office success, grossing $87.7 million against its budget of $3 million. The resulting financial success led to a sequel, released in 2015.

It has since developed a reputation for scariness and is considered a cult classic. A 2020 study by Broadband Choices named Sinister the scariest film ever made, based on an analysis of viewer heart rates.