Fictional doomsday devices

fictional space station used as a superweapon by the Galactic Empire in the Star Wars universe

thumb|The fictional ice-nine is depicted as being capable of causing any liquid water to permanently freeze unless heated far above room temperature. Ice-nine is a fictional material that appears in Kurt Vonnegut's 1963 novel ''Cat's Cradle''. Ice-nine is described as a polymorph of ice which instead of melting at 0°C (32°F) melts at 45.8°C (114.4°F). When ice-nine comes into contact with liquid water below 45.8°C, it acts as a seed crystal and causes the solidification of the entire body of water, which quickly crystallizes as more ice-nine. As humans are 55-60% water, ice-nine kills nearly i