Cybermen

Cybermen are, as their name suggests, men that have been cyberised. Instead of being part-man part human like some Sith Lords we could mention or something from Star Trek, the Cybermen are merely robot cases with human brains wired into the top. Along with the Daleks they are the worst enemy of the Renegade Time Lord known as the Doctor.

They have decided to 'upgrade' all humans into Cybermen so the League cast them into another universe to prevent them from causing harm. Despite this they still manage to escape on several occasions, but when they do its always when the league need that extra bit of military force so they often end up fighting with the League, the Humans and the Daleks, not against them. An example of when this has NOT occured would be the Dalek-Cyberman War.

Despite being weaker than Daleks they are significantly stronger than Humans (but then again, who isn't?), with the average Cyberman being ten times stronger than a human. However, they are vulnerable to electricity and high-pitched noises. Rumour has it that some Cybermen are even vulnerable to the element Gold.