Let the Right One In (Swedish: Låt den rätte komma in) is a 2008 Swedish romantic horror film directed by Tomas Alfredson, based on the 2004 novel of the same title by John Ajvide Lindqvist, who also wrote the screenplay. The film tells the story of a bullied 12-year-old boy who develops a friendship with a strange child in Blackeberg, a suburb of Stockholm, in the early 1980s.

A film adaptation of Lindqvist's novel began development in 2004 when John Nordling acquired the rights to produce the project. Alfredson, unconcerned with the horror and vampire conventions, decided to tone down many elements of the novel and focus primarily on the relationship between the two main characters and explore the darker side of humanity. Selecting the lead actors involved a year-long process with open castings held all over Sweden. In the end, Kåre Hedebrant and Lina Leandersson were chosen for the leading roles. Leandersson's role in the film was dubbed by Elif Caylan. Principal photography took place in 2007 in Luleå, with additional filming in Blackeberg. The film was produced by EFTI, Sveriges Television and Filmpool Nord, with support from the Swedish Film Institute, Nordisk Film & TV Fond, WAG and Canal+.

Let the Right One In premiered at the Gothenburg Film Festival on 26 January 2008, where it received the Nordic Film Prize. It was released in Sweden on 24 October 2008 by Sandrew Metronome. The film received critical acclaim, with praise for the performances of the two leads, the cinematography, screenplay, and direction. It won several awards, including the Founders Award for Best Narrative Feature at the Tribeca Film Festival, as well as four Guldbagge Awards, including Best Director for Alfredson, Best Cinematography for Van Hoytema, and Best Screenplay for Lindqvist. It also won the Saturn Award for Best International Film and the Empire Award for Best Horror Film. At the 63rd British Academy Film Awards, the film was nominated for Best Film Not in the English Language. An American remake, titled Let Me In, was released in 2010.