'You will become like us!' ~ Cyberman
They were created by Dr. Kit Pedler and Gerry Davis in 1966, first appearing in the serial, 'The Tenth Planet' which was the last episode featuring the First Doctor: William Hartnell.
A Parallel universe version of the Cybermen appeared in the 2006 series in the two part story: Rise Of The Cybermen and The Age Of Steel'. 'They have also appeared in the spin off series' Torchwood' in the episode 'Cyberwoman'. They would later return in the 2008 christmas special 'The Next Doctor' introducing two types of Cybermen: The Cyber-Shades and The Cyber-King.