Jennifer's Body is a 2009 American comedy horror film directed by Karyn Kusama and written by Diablo Cody. Starring Megan Fox, Amanda Seyfried, Johnny Simmons, J. K. Simmons, Amy Sedaris, and Adam Brody. The film follows Jennifer Check (Fox), a demonically possessed high school student who kills her male classmates and devours their flesh in order to survive, while her bookworm best friend Anita "Needy" Lesnicki (Seyfried) must find a way to end her killing spree.

Working with Cody again following their collaborative efforts on Juno (2007), Jason Reitman stated he and his producers "want to make unusual films". Cody said she wanted the film to speak to female empowerment and explore the complex relationships between best friends. As a tie-in to the film, Boom! Studios produced a Jennifer's Body graphic novel, released in August 2009.

Jennifer's Body premiered at the Toronto International Film Festival on September 10, 2009, and was theatrically released in the United States and Canada on September 18, 2009. The film was a commercial failure, grossing $31.6 million against its $16 million production budget, and received mixed reviews from critics, with its dialogue, emotional resonance, and performances of the cast being praised, while the narrative and tone were criticized.

Following revelations that the film's poor marketing campaign was the result of the studio's desire to capitalize on Fox's sex appeal and gear the film towards a younger male audience, Jennifer's Body has undergone a critical reevaluation in the years since its release, and has been described as a feminist cult classic.