Okay, there's a definitive re-rebeginning. Cylons are actual characters/entities other than shitty US presidents (which no on voted on anyway).
So, we'll begin with Cylons and NeoCylons (from Battlestar Galactica). The only thing I remember about the original version is Lauren Greene and that Noah kid and his little dog. So, I did some research...
Cylons: Now, originally, they were created as robotic workers. You see, they're sort of cy
borgs but different. There are different types of these things, but from what I've come to understand, they want to get rid of humans. So, some of them even look human. In the old series, they could kind of look human, but a trained eye could tell the difference.
This is your old version. Sure, they were big metal and kicked butt. There were many that were essentially
the ship. They were stationary units that were humanoid, but perfectly maintained the operations of the ship. At one time, you could talk to them, but later...It wouldn't have been a good idea.
Now the new and improved versions can do much more. They can blend into human society without any notice. They have a larger variety of Cylons (I'll show you two). This new kind almost has an intelligence that isn't programmed.
Centurian (warrior, laborer, guard, etc)
One of the big Cylons (Cylon 6)
So, for this villain question, it's not the villain, but the model? Kind of like asking a James Bond fanatic, "When was Ernst Stavro Blofeld at his worst?