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Mondas was the twin planet of Earth and original homeworld of the Cybermen. In ancient times, it was dislodged from its old position out into space when the Moon was formed. The Cybermen eventually learned to pilot their planet and took Mondas back to Earth, where it was destroyed.

Native life[]

Originally, the Mondasians resembled the humans of Earth in every respect. (TV: The Tenth Planet, AUDIO: Spare Parts) Some accounts show that in the same way that parallels to humans existed on Mondas, Lizard Kings and Sea Devils shared the planet with dinosaurs, Cybermen, (COMIC: The Dead Heart) and apes. (COMIC: The Prodigal Returns) Golgoth, a bipedal reptilian god in physical form, also lived on Mondas at this time. (COMIC: The Cybermen)

The Museum of the Last Ones had specimens of extinct species from Mondas. (PROSE: The Last Dodo)


Mondas was identical to Earth, even down to the size and shapes of its continents. The one major way that it differed to Earth was that its continents were upside down in relation to Earth. However, it had no visible clouds in its atmosphere at that time. (TV: The Tenth Planet)



According to one account, Mondas originated as Marinus, a planet previously visited by the First Doctor, the Cybermen having "quick-evolved" from the Voord. This account claimed that Marinus was known as Planet 14. (COMIC: The World Shapers) This was contradicted by the Twelfth Doctor, who knew that while Cybermen did evolve on Marinus, they originated separately from the Mondasian Cybermen, through parallel evolution. (TV: The Doctor Falls)

According to another account, Mondas was created by the Constructors of Destiny as an experiment of sorts to see how it would differ from Earth. (PROSE: The Quantum Archangel)

Originally, Earth and Mondas occupied the same orbit in the solar system. It was stated that "Mondas" was another name for Earth in one of the ancient languages. (TV: The Tenth Planet)

Under Lizard King rule[]

Mondas had, like Earth, at one time, an intelligent reptile species. (COMIC: The Cybermen)

A Lizard King begins to vivisect a captured Cyberman. (COMIC: The Prodigal Returns)

A cosmic cloud once appeared near Mondas. A Cyberman from the future came through the cloud and was captured by the Lizard Kings. At this point, the Lizard Kings had never encountered Cybermen before. They were intruiged by the cloud the Cyberman came from and sent a modified ape-servant through the cloud to investigate if it was a viable way to escape the rogue planet which was approaching Mondas fast.

The Lizard Kings never left Mondas, (COMIC: The Prodigal Returns) and the sudden arrival of a moon between Earth and Mondas caused an upset in the gravitational equilibrium of Mondas, causing it to escape its orbit (AUDIO: Spare Parts) and begin drifting on a journey to "the edge of space". (TV: The Tenth Planet)

While parts of Mondas still had a tropical climate, the Lizard Kings encountered the Cybermen of their own time and warred with them. (COMIC: The Dead Heart) Golgoth appeared and destroyed all but one Cyberman and finally destroyed the lone survivor. (COMIC: The Cybermen)

By the time that Mondas was well and truly separated from Earth, the Lizard Kings had fallen and the Cybermen became the new rulers of Mondas. (COMIC: The Prodigal Returns)

Evolution of the Cybermen[]

A Cyberman begins to vivisect an ape that was modified by the Lizard Kings. (COMIC: The Prodigal Returns)

A cosmic cloud appeared near Mondas, providing a temporal link to its past. After an ape modified by the Lizard Kings came through the cloud and was captured by Cybermen, they became curious about the cloud and decided to send a scout through it see if there were more apes that could be converted into Cybermen on the other side. (COMIC: The Prodigal Returns)

Some centuries after, Cybermen had been wiped out and human-appearing Mondasians of roughly 20th century technological development had replaced them. Archaeologists discovered remnants of the Cybermen. (COMIC: The Ugly Underneath)

Further away from the life-giving warmth of Sol, conditions on the planet grew steadily worse. This forced the inhabitants to relocate underground in order to survive. They had by this time developed a society parallel to that of 1950s England. The Cybermen took over and enforced cyber-conversion for the surviving Mondasians. (AUDIO: Spare Parts) One Cybermen faction, the Mondans, decided to stay on their home planet. Another group, the Faction, more committed to total cybernetic conversion in comparison to the Mondans, pushed outwards in the solar system and colonised Planet 14. (PROSE: Iceberg)

The CyberMondasians developed a drive which used electro-magnetic energy to push the whole planet through space. (PROSE: Iceberg)

Return of Mondas[]

Their only recourse now was to use Mondas' last remaining energy to return to the Earth's orbit and plunder its energy. (TV: The Tenth Planet)

In 1873, Mondas was located 200 light-years from Earth. (AUDIO: The Silver Turk)

In 1903, after receiving a wealth of information from the future, Grigori Rasputin foresaw the return of Mondas. (AUDIO: The Wanderer)

In 1954, a Cyber-Warship reported to Mondas Central. (COMIC: The Good Soldier)

In 1984, the Sixth Doctor left a damaged Cyber-Leader from the far future on Mondas knowing that it would be destroyed with the rest of the planet two years later. The Cyber-Leader, sporting the CyberNeomorph design, was discovered by the CyberMondasians. (AUDIO: The Reaping)

In December 1986, the Cybermen invaded the Snowcap tracking base in Antarctica while Mondas drew closer, draining Earth's energy to replace and supplement its own. However, the energy absorbed was too much, and Mondas disintegrated. The destruction of Mondas destroyed all of the Cybermen on Mondas and also killed all of the Cybermen on Earth, who were dependent upon Mondas for energy. As the planet plundered Earth's energy, the First Doctor's life-force was caught up in the maelstrom, triggering his regeneration into his second incarnation. (TV: The Tenth Planet) The Sixth Doctor would note Mondas's destruction as being part of the Web of Time as he thwarted an attempt made by future Cybermen in the previous year to save Mondas. (TV: Attack of the Cybermen)

Aftermath of Mondas' destruction[]

The official statement on Earth attempted to cover up the Cyberman invasion by claiming Mondas was an asteroid, known as "the Mondas Asteroid", which went supernova before colliding with Earth. During Earth's war with the Myloki between 2066 and 2068, Alex Storm found UN documents which revealed that Mondas was actually a planet. However, these documents were destroyed by "some ignorant clerk" to "save space". (PROSE: The Indestructible Man)

After Mondas was destroyed, a group of Cybermen relocated to Lonsis. (AUDIO: Human Resources)

Other realities[]

In one of the infinite parallel universes of "possible space", (COMIC: Fire and Brimstone) the planet Mondas's environment was ruined by its careless inhabitants, who ended up modifying themselves into the vain, "cybotic" pirates known as the Cybs. The planet was eventually destroyed at some point after 1994 in an effort to destroy the Cybs. (PROSE: The Chronicles of Doctor Who?)


In 1988, a Cyber-Leader leading a squad of CyberIsomorphs revealed that he planned to use the Nemesis to transform Earth into "the New Mondas". (TV: Silver Nemesis)

In the 2006 of an alternate timeline, Jack Harkness described the Cybermen to Jackie Tyler as "a race of cyborgs from the long-dead planet of Mondas". (COMIC: Supremacy of the Cybermen)

When the Tenth Doctor had discovered a way to turn the Kotturuh's necrotic retro-virus against them, he pondered about how the planets in his time would evolve without death's influence, theorising that the Mondasians would never become the Cybermen if their flesh were never to wither. (PROSE: The Knight, The Fool and The Dead)

Facing the Cybermen on a colony ship, the Twelfth Doctor recalled Mondas as the first of the worlds where they rose. (TV: The Doctor Falls) Missy previously discovered the ship itself originated from Mondas though it was never revealed at which point in the planet's history the colony ship was launched. (TV: World Enough and Time)

Behind the scenes[]

Surface of Mondas as seen in The Cyber Story.

A city on Mondas under the dome (see above image) as seen in The Cyber Story.

Origins of the concept[]

The idea of a parallel Earth opposite in orbit to Earth itself has occurred in pre-modern astronomy (Counter-Earth) and some other works of science fiction, though modern astronomers consider this unfeasible due to the orbital mechanics involved. The idea had earlier almost appeared in Doctor Who in the proposed Malcolm Hulke story The Hidden Planet. Apart from this, the idea occurs in countless comics, movies, novels and short stories.

Continuity conflicts and ambiguities[]

The Cybermen origin story in The World Shapers portrays Marinus, Mondas, and the mysterious Planet 14 referenced in The Invasion as the same place.

Iceberg and Doctor Who: Cybermen by David Banks, who had also played the Cyber-Leader on Doctor Who, explain it differently. According to the later, non-narrative reference guide, which this wiki does not consider to be a valid source, the drive that propelled Mondas through space was developed during the journey to "the edge of space" in order to effect a controlled return to their original orbit.