The Robot City
Probably the biggest -- and strangest -- killer robot in science fiction appears in "The City," a short story from Ray Bradbury's 1951 anthology "The Illustrated Man." The tale begins when a rocket from Earth lands on a distant planet, Taollan, and a team of astronauts discover an immense mechanized city, run by a computer network, which oddly has remained running even though it doesn't seem to have flesh-and-blood inhabitants anymore.
When the crew's leader tells his men to draw their guns as they probe the seemingly empty metropolis, one responds: "The city's dead, why worry?" Not exactly, though. The city itself is a giant synthetic organism, which is quietly observing their movements, weighing and measuring them, and even noting their human aroma. When the crew isn't looking, the city springs a trapdoor and abducts the captain, who is promptly vivisected to verify that he is an Earthling. As it turns out, the city is a trap, left behind by Taollan's original inhabitants.
Twenty thousand years before, a previous team of human explorers enslaved and eventually killed off the extraterrestrial species with infectious disease. Before they died out, the Taollanians built the robot city so that it would keep running, until humans someday wandered back to the planet. The robot city captures the rest of the astronauts, kills them, and replaces their insides with robotic parts and wiring. Then the city sends the astronauts back to Earth in their spaceship -- which is infected with a virus that will wipe out humanity. The story ends with these chilling words: "Slowly, pleasurably, the city enjoyed the luxury of dying" [source: Bradbury].