? As any science fiction fan knows, the Cylons were a race of sentient machines in the TV series "Battlestar Galactica". The series was originally on from 1978 to 1979. The Cylons that appeared in that show were obviously metal constructs. They had a glowing, red eye that moved from side to side and their voices sounded like computerized voice synthesizers. The series was revived in 2004 with a new cast and brand new Cylons. The Cylons of this newer series looked like humans. Even their internal structure was so like a human being that it was difficult for real humans to identify them. The Cylons were able to pass medical exams without doctors being able to tell they weren't human. The humanoid Cylons were designed to be capable of not only appearing human outwardly and under examination, but they could also perform any function that a human could including having sex and even having a baby. They also possessed the full range of human emotions. The original Cylons were created by humans. The later flesh and blood models were created by earlier Cylons and were simply the evolution of the Cylon race. Their original purpose was not to be spies, but they did eventually infiltrate the human population and became exactly that. Though they are so much like humans, they do have some advantages. Whenever a Cylon is killed, its awareness is transferred to another physical body. This makes them very difficult for the humans to get rid of. Their ultimate goal is to destroy all humans, and with their advantages, they are very hard to stop.