The Cybermen were originally built as an upgrade of the residents of the planet Mondas, to help them survive and bear the pain of the harsh conditions they were living in. Unfortunately, as the Mondasians became more and more machine-like, the less their minds could cope with it. As a result, they inhibited their own emotions, not only to keep themselves sane, but also to remove the final vestiges of pain within them - the pain caused by sorrow, anger, and loss. These were the first Cybermen.