The cylons are a robotic race whose aim is to annihalate the life form known as man. The cylons originally were the robotic servants of a reptilian race. But the cylons defeated their former masters in a great civil uprising. From then on out robotic cylon life was to spread.
Man seems to be the sole lifeform that has been able to resist the cylons thus far.
The cylon centurian is the backbone of the Cylon war machine. There are two types of Cylon Centurian. The standard silver centurian is the lowest in stature in the Cylon society because of its less sophisitcated intellectual systems. Another centurian type known as the Gold Centurian or leader centurian is the most common field commander of all low level operations. Gold Centurians lead Cylon Raider attack ship crews which consist of two of the lesser Silver Centurians and one of the more advanced gold centurians.