Let Sleeping Corpses Lie (Spanish: No profanar el sueño de los muertos, lit. 'Do Not Profane the Sleep of the Dead'; also known as The Living Dead at Manchester Morgue and Don't Open the Window) is a 1974 zombie horror film directed by Jorge Grau, and starring Cristina Galbó, Ray Lovelock and Arthur Kennedy. It focuses on two protagonists who are harassed by a local police investigator in the English countryside and are implicated in murders committed by zombies who have been brought to life by a farming tool designed to kill insects via ultra-sonic radiation.

A co-production between Spain and Italy, Let Sleeping Corpses Lie premiered at the Sitges Film Festival on 30 September 1974, where it won awards for Best Actress (for Galbo) and Best Special Effects. Jorge Grau won the CEC Award for Best Director. In the following years, the film has become a cult classic.