Battlestar Galactica

The Cylons were created by the people of the Twelve Colonies. Intelligent robots, they were used as slaves and soldiers to fight humanity's wars. But the Cylons became sentient and they rebelled. Man and machine fought to a bloody stalemate, then the Cylons withdrew to a remote region of space. A truce between the Twelve Colonies and the Cylons lasted for 40 tense and silent years. Then, on the 40th anniversary, a stunning blonde — a Cylon in human form — met the human envoy … moments before the Cylons vaporized the station and launched a genocidal attack on the Twelve Colonies.
(source : Sci-Fi)