Let the Right One In is a 2004 vampire novel by Swedish writer John Ajvide Lindqvist. The story centers on the relationship between a 12-year-old boy, Oskar, and a centuries-old vampire child, Eli. It takes place in Blackeberg, a working-class suburb of Stockholm, in the early 1980s. The book grapples with the darker side of humanity, including such issues as existential anxiety, social isolation, fatherlessness, divorce, alcoholism, school bullying, pedophilia, genital mutilation, self-mutilation, and murder.

Let the Right One 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.