What is a Cylon?
It depends on how and from what series you view it. To our left we have our typical "toaster" Cylon Centurion from the original Battlestar Galactica. To our right we have a new and very different Cylon that takes the form of a human being from the Re-imagined Series. There still are big and intimidating Cylon Centurions kicking around, themselves new, but it's the humanoid models which are the biggest threat to the Fleet.