The Krell were fictional natives of the planet Altair IV in the science fiction film Forbiden Planet. Two thousand centuries before the film is set, their race died out when they completed their project to gain freedom from "instrumentality" - that is, freedom from the use of tools and devices. A Great Machine would instead, read their thoughts and instantly make them into reality. Unfortunately, the 8,000 cubic mile (33,000 km³) machine they created for this purpose also gave physical form to all of their subconscious hatreds - unfamiliar emotions that had seemingly been eradicated from their society, monsters from the id, and killed them all in the space of a single night. The unstoppable machine committed genocide.