Cylons

The Cylons (Cybernetic Lifeform Node) are a race of sentient beings in the Battlestar Galactica Universe. Conceived of as military robots, the Cylons quickly entered industrial and domestic sectors, and over a period of six years became widespread across the Cyrannus star system. Inspired by their belief in the One True God, they launched a cataclysmic slave rebellion against their human masters, which became a genocidal war for both parties. In 1960, the Cylons ended their war and left mankind to pursue their own evolution on a colony of their own, but forty years later returned to exterminate the near totality of mankind. In the next four years their culture went through a series of shifts which led to the collapse of their political structure, spawning a genocidal civil war.