Science fiction author Philip K. Dick was a master of the killer robot genre, partly because he imagined a future in which technology would become so advanced that the distinction between humans and machines would blur. And that works, because we all know how over-the-top murderous humans can be. Dick achieved his greatest fame from the 1982 film "Blade Runner," based upon his novel "Do Androids Dream of Electric Sheep," which depicts a policeman (portrayed by Harrison Ford) in pursuit of a killer android named Roy (Rutger Hauer) -- who, as it turns out, is not so different from his nemesis. But Roy's menace is tempered by one fact: He murders not out of blood lust, but in a futile effort to survive past his expiration date.
For pure kill-all-humans evil, we're better off with the Claws from Dick's 1953 short story "Second Variety." In that tale, written during the Cold War, the Claws are autonomous self-replicating robots created by the U.S. to fight the Soviets in the wake of a nuclear war that scorched the planet and reduced it to a nightmarish wasteland. The problem is that the Claws, who are anthropomorphic, do their job too well. After they kill off the Soviets, they need a new reason to exist, and thus set their sights on eliminating the Americans -- and eventually each other [source: Dick]. The Claws were the inspiration for the killing machines in the 1995 movie "Screamers," which takes the Dick story and sets it on a mining colony in another solar system.