The Blair Witch Project is a 1999 American supernatural horror film written, directed and edited by Daniel Myrick and Eduardo Sánchez. It is a fictional story of three student filmmakers—Heather Donahue, Michael C. Williams, and Joshua Leonard—who hike into the Black Hills near Burkittsville, Maryland, in 1994 to film a documentary about a local myth known as the Blair Witch. The three disappear, but their equipment and footage are discovered a year later. The purportedly "found footage" is the movie the viewer sees.

Myrick and Sánchez conceived of a fictional legend of the Blair Witch in 1993. They developed a 35-page screenplay with the dialogue to be improvised. A casting call advertisement in Backstage magazine was prepared by the directors; Donahue, Williams and Leonard were cast. The film entered production in October 1997, with the principal photography taking place in Maryland for eight days. About 20 hours of footage was shot, which was edited down to 82 minutes. Shot on an original budget of $35,000–60,000, the film had a final cost of $200,000–750,000 after post-production edits.

When The Blair Witch Project premiered at the Sundance Film Festival at midnight on January 23, 1999, its promotional marketing campaign listed the actors as either "missing" or "deceased". Owing to its successful run at Sundance, Artisan Entertainment bought the film's distribution rights for $1.1 million. The film had a limited release on July 14 the same year, before expanding to a wider release starting on July 30. While critical reception was mostly positive, audience reception was polarized.

The Blair Witch Project grossed nearly $250 million worldwide, making it one of the most successful independent films of all time, as well as the 29th most profitable horror film, while also being a sleeper hit. The film launched a media franchise, which includes two sequels (Book of Shadows and Blair Witch), novels, comic books, and video games. The film is credited with reviving the found-footage technique which was later used by similarly successful horror films such as Paranormal Activity and Cloverfield.