Origin : Mondas
"You belong to us. You shall be like us!" The Cyber Controller - Tomb Of The Cybermen
The Cybermen are perhaps the most relevant Doctor Who monster in terms of their origins.
Inspired by technological advances in medical science to improve the human body. It followed this through to a natural nightmarish conclusion : where the technology had taken over the appearance and the very freewill of the being.
Even today, the pace of medical discovery continues unabounded and the very everyday use of bionic hip replacements or artificial heart valves means the Cybermen's appeal is no less diminished, nearly 50 years on.
In the 1960's though, it was pioneering research done by people like Dr Christopher Magnus Howard "Kit" Pedler which pointed to a future where the body could be 'upgraded' with robotic replacements parts. It was this notion that Dr Pedler brought to the Doctor Who production team, having been hired as a consultant. In 1966, he put forward a suggestion for a race of part human part robotic cyborg's which came to be known as 'The Cybermen'.
Thrown into the mix was the eradication of feelings, specifically the ones which get in the way of a warlike race : compassion, trust, loyalty, honesty etc.
It was this which set the Cybermen on a path to conquer and 'upgrade' all those races to match their own, which they now seen as inferior.
It was in William Hartnell's Tenth Planet - 1966 that the Cybermen made their first appearance, as residents of the "10th" planet called Mondas - an Earth twin.
Mondas had been knocked out of a much closer orbit to the sun by the Earth and flung to the edges of the solar system. The Mondasians had took drastic measures to survive this catastrophe, by using technology to redesign themselves.
From the start, the Cybermen were hellbent on seeking revenge on the Earth for this, intent on destroying it with their cyber Z bombs.
"Yes! We [Cybermen] were exactly like you once, but our cybernetic scientists realised that our race was getting weak. Our life span was getting shorter, so our scientists and doctors devised spare parts for our bodies until we could be almost completely replaced. Our brains are just like yours, except that certain weaknesses have been removed....." Cyberman
The Doctor managed to foil the Cybermen and the planet Mondas was destroyed in the ensuing fight, the First Doctor paid a heavy price for this though and had to regenerate.
The Cybermen made their next appearance in the eerily effective Moonbase - 1967, in which another invasion of Earth was to be launched - via capture of an Earth Moonbase. The Cybermen had poisoned the Moonbase's inhabitants and were infiltrating the base - a few at a time. Their appearance had radically changed since the Doctor's last encounter, they were less bulky looking and more streamlined.
Many of the Cybermen had left Mondas prior to its destruction and various splinter factions developed. Some ended up hiding on Earth and others travelled off in space freighters to await the optimum moment for invasion.
One group of Cybermen travelled to the planet Telos, after subjugating the local populace, dug themselves a Tomb and went into hibernation.
Their plan, to await discovery by an intelligent race, who themselves could be forcibly converted into more Cybermen.
It was unlucky then, perhaps, that the Second Doctor was on of the Archaeology party which happened across the Cybermen in The Tomb of the Cybermen, 1967.
As a race of beings, they were constantly upgrading and improving themselves. They began with huge headlamp appliances and bulky weapons which were fixed to their chests.
Over time, their chest weapons moved onto their forehead. Finally, their weapon became a seperate device carried but still attached to the Cyberman by means of a wire.
The Cybermen made use of various technologies including powerful Cyber bombs to use against their enemies and Cybermat's, small silver metal rodents which could be used for surveillance or subterfuge.
Although the Cybermen had gone through many changes over the years, they still retained certain characteristics which made them instantly identifiable.
They retained their signature handle like attachments over the top of their head, wide gaping mouth slots and round emotionless eyes.
In additon to the above, there was a shortlived shiny Silver variety in Silver Nemesis - 1989 and a black stealth model in Attack Of The Cybermen - 1984.
The Cybermen were individually intelligent, calculating creatures but were controlled by means of a central hive intelligence. The Cyber Leader (or Controller) usually distinguished themselves by means of a large cranium or a differently coloured helmet.
The Cybermen's only real weakness was gold, it blocked their respirators and suffocated them. In Revenge Of The Cybermen - 1974, the Cybermen attempted to destroy an asteroid made out of pure gold, which was heading their way. 
In Earthshock - 1982 the Doctor killed the Cyber Controller by means of Adric's gold sheriff badge and in Silver Nemesis the locals devised gold tipped arrows to shoot the Cybermen with from primitive bows.
The Cybermen were back for a third go at taking over Earth in Invasion, 1968, thwarted for a third time by the Second Doctor who had some handy nuke's to shoot the Cyber fleet out of the sky.
The Cybermen were abducted and taken to Gallifrey and forced to take part in the Timelord's dastardly games in The Five Doctors - 1983, against all five incarnations of the Doctor.
The Cybermen were battered from all sides, tricked by the Master into crossing an electrified trap floor and frying themselves and attacked by a Rastan Warrior robot, which decimated an entire Cyberpatrol.
"Wasn't that a little ruthless? Even for you!" Tegan [after the Master has killed a Cyberpatrol]
"In one of the many miserable wars on your planet, they [Cybermen] used to drive sheep across minefields!" The Master
Attack of the Cybermen and the Sixth Doctor ran into the Cybermen again, hiding in a London sewer plotting to divert Halley's Comet into hitting the Earth. Their last original series appearance was in the Seventh Doctor's Silver Nemesis.
The Cybermen have proved to be a popular monster throughout Doctor Who and many fans still hark back to the original Cybermen as their favourite over the stompy, brainless, Robocop-like Cyber's in the new series.
The first appearance, although a little silly now, still invokes an alien-esque life form in the jerky mouth opening and electronic voice which didn't betray a hint of emotion.
Later incarnations of the Cybermen got more streamlined and more robotic with each appearance. The Cybermen's aim was similar to the Dalek's, conquer and oppress and "upgrade" their enemies into fresh Cyber units but the Cybermen's appeal were due to their fact they were still vaguely humanoid, unlike the Dalek's.
The final horror was, of what the Mondasian's had done to themselves, which is never lost.
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