The Cybermen are a race of cybernetically enhanced humanoids. By parallel evolution, the Cybermen have independently developed several factions on various planets throughout time and space, such as in the alternate Earth and the planets Mondas and Telos. The Cybermen can differ in design depending on their origin, but they all have a core concept in common: that emotion is weakness; which means that the they are designed to lack any kind of emotion and individuality. Their goal is usually to physically and mentally transform all humans and other humanoids around them into Cybermen via a process called ‘cyberconversion’, or ‘upgrading’. The Doctor has fought the Cybermen several times, sometimes suffering heavy losses, but ultimately being successful in stopping the Cybermen.