From a race of cybernetically modified humanoid that come from two groups, the Mondasian Cybermen from the planet Mondas (Earth's twin planet in the Doctor's Universe) and those created by Cybus Industries on Earth in an alternate universe.Nearly all Cybermen of Mondas are silver, although they also come in black for stealth. Their major weakness is the element gold, which chokes their respiratory systems. Guns have little effect on them, although they are sometimes vulnerable to larger charges.They do not display emotion and lack individuality and names. They often attempt to make humans and others into Cybermen in a process called cyber conversion or upgrading.