Let's Scare Jessica to Death is a 1971 American psychological horror film co-written and directed by John Hancock in his directorial debut, and starring Zohra Lampert, Barton Heyman, Kevin O'Connor, Gretchen Corbett, and Mariclare Costello. The film depicts the nightmarish experiences of a psychologically fragile woman who comes to believe that another strange, mysterious young woman she has let into her home may actually be a vampire.

Initially conceived by writer Lee Kalcheim as a satirical horror film about a group of hippies preyed upon by a monster in a lake, the screenplay was significantly reworked after director Hancock signed on to the project. Hancock took certain elements from Kalcheim's script, but opted to write a straightforward horror film set at a remote farmhouse. Inspired by Henry James' novella The Turn of the Screw and Robert Wise's film The Haunting (1963), Hancock wanted to center the screenplay on a protagonist whose credibility interpreting events could be questioned by the audience so they could use their imagination. Filming of Let's Scare Jessica to Death took place in various towns and villages in Connecticut, largely in Middlesex County.

Though completed without a distributor, Let's Scare Jessica to Death was purchased by Paramount Pictures, who gave it a wide release in the United States on August 27, 1971, and heavily marketed it as a vampire film. It received mixed reviews from critics at the time, with some praising its atmosphere but criticizing the performances as inconsistent and offering varying responses to the screenplay's ambiguous nature. Though criticism of the film has been divided, it went on to attain a cult following, and some film scholars have drawn comparisons to Joseph Sheridan Le Fanu's novel Carmilla (1871).

In 2006, the Chicago Film Critics Association pronounced Let's Scare Jessica to Death one of the scariest films ever made, and in 2012, it was ranked in the British Film Institute's Sight & Sound poll as the 849th greatest film of all time. The film was scarcely available in home media formats for several decades, available only on Betamax and VHS until 2006, when Paramount issued a DVD version. A Blu-ray was released by Scream Factory in January 2020, followed by a 4K UHD Blu-ray by Vinegar Syndrome in 2025.