The Tomb of the Cybermen is the first serial of fifth season in the British science fiction television series Doctor Who. It is the earliest serial starring Patrick Troughton as the Second Doctor known to exist in its entirety and it was the only serial of the fifth season known to survive for many years, from its recovery in 1991 until more missing episodes were found in 2013. It originally aired in four weekly parts from 2 September to 23 September 1967. It also introduces the Cyber Controller and the Cybermats.
On the planet Telos, an archeological expedition uncovers a hidden entrance in a mountain. The TARDIS lands nearby, and the expedition is joined by the Doctor, Jamie and Victoria. Parry, the expedition's leader, explains that they are here to find the remains of the Cybermen, who apparently died out five centuries before. The expedition is funded by Kaftan, who is accompanied by her giant manservant Toberman and her colleague Klieg. One of the men is electrocuted opening the doors, but the party manages to enter the chamber. They find a control panel and a large, sealed hatch. Parry and Klieg try to open it as Toberman slips out.
The Cybermen are a fictional race of cyborgs who are among the most persistent enemies of the Doctor in the British science fiction television programme, Doctor Who. Within the context of the series, the Cybermen were originally a wholly organic species of humanoids originating on Earth's twin planet Mondas that began to implant more and more artificial parts into their bodies as a means of self-preservation. This led to the race becoming coldly logical and calculating, with every emotion deleted from their minds.
They were created by Dr. Kit Pedler (the unofficial scientific advisor to the show) and Gerry Davis in 1966, first appearing in the serial The Tenth Planet. They were featured numerous times, up until the show's cancellation.
Following the 2005 revival of the show, the Cybermen returned with a new origin story in a parallel universe, in the 2006 series' two-parter "Rise of the Cybermen" and "The Age of Steel", and have been recurring villains again ever since. A further redesign took place in the 2013 episode "Nightmare in Silver", showing technologically advanced Cybermen with the same origins as in the original series, depicted as being able to instantly upgrade themselves to fix flaws and weaknesses.