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.

John Ajvide Lindqvist is a Swedish writer of horror novels and short stories.