Let Sleeping Corpses Lie (Italian: Non si deve profanare il sonno dei morti, lit. Do Not Profane the Sleep of the Dead; 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 Spanish-Italian science fiction zombie horror film written and directed by Jorge Grau and starring Ray Lovelock, Arthur Kennedy and Cristina Galbó. 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.

After being presented at the Sitges Film festival in Spain on September 30, 1974, the film was released in Italy on 28 November 1974 and was later released throughout 1975 in the United States and the United Kingdom under varying titles. In total, the film was released under more than 15 different titles internationally. In the following years, the film has become a cult picture.