The Cybermen
The Cybermen are a race of humanoids who dwell from the planet of Mondas, a twin of Earth. The Cybermen swapped their organic parts for robotic components, seeking to become totally robotic. This they achieved and became like machines, but only after there had assimilated humans into their race and used them as experiments for new Cybermen. The Cybermen are almost indestructible and can only be killed by either a single violent attack, Cyber-weapons or with gold. Their home planet, Mondas, was destroyed by the Earth's power. The Cybermen tried to alter the time-line to prevent this from happening, but the 6th Doctor managed to defeat them.
Strengths:
Very strong
Almost indestructible
Totally ruthless
Weaknesses:
Very arrogant
Vulnerable to gold
Appearances:
The Tenth Planet, The Moonbase, The Tomb of the Cybermen, The Invasion, The Wheel in Space, Carnival of Monsters, Revenge of the Cybermen, Earthshock, The Five Doctors, Attack of the Cybermen, Silver Nemesis,