The Cybermen are from Earths twin planet Mondas. The Cybermen began experimenting with cybernetic parts in order to survive, eventually all their emotions were removed and they became less and less human. The Cybermen that appeared in the 2006 series were different, they were from a parallel Earth.
The Cybermen were originally created by Dr Kit Pedler and Gerry Davis in 1966. Dr Kit Pedler was a medical researcher at London University and became Doctor Who’s unofficial scientific advisor, he helped create the idea of the Cybermen as well as writing the first few stories. The Cybermen originally appeared in the first Doctor’s (William Hartnell) final story. The producers hoped that the Cybermen would match the success of the Daleks and become the Doctors new main enemy.