Mondasians, also called Mondans (PROSE: Iceberg) or, especially among themselves, simply humans (TV: World Enough and Time) were the natives of the planet Mondas who eventually created the technology that gave rise to at least two species of Cybermen: one on Mondas itself, and another onboard a Mondasian colony ship.
Just like their planet was Earth's twin, the Mondasians themselves were also very close genetically to the Terran humans and were described by the Eighth Doctor as humanity's "closest cousins". According to the Doctor, the two species were the only ones on which the process of cyber-conversion originally worked, (COMIC: The Flood) although some Cyberman groups later developed technology that allowed them to convert other species as well. (TV: Nightmare in Silver, COMIC: Assimilation², Supremacy of the Cybermen)
Amongst Cybermen, the term Mondan had a peculiar meaning. According to at least one account, it referred to those Cybermen who stayed on Mondas and were philosophically opposed to the CyberFaction. (PROSE: Iceberg) Mondans, according to the Faction, were not fully dedicated to the pursuit of logic and retained a bigger portion of their biological systems after conversion. Mondans, in this sense of the word, were eventually wholly eradicated after Mondas exploded. Thus, in this narrower sense of the word, Mondans were the form of Cybermen that the First Doctor encountered shortly before his regeneration. (TV: The Tenth Planet) However, this usage was not widely used or even known by other species. For most races, Mondan or Mondasian simply meant "the species that formed the biological core of the Cybermen".
Like many names, both Mondasian and Mondan were sometimes used as demonyms to mean "a thing which came from Mondas or was produced by Cybermen". For instance, the android Sara once told the Seventh Doctor that "there [were] android agents scattered all across the galaxy, scouring space for Mondasian relics", because the androids thought that Mondasian technology would give them an advantage in their war against humanity. (AUDIO: Kingdom of Silver)
Mondas was ruled by the Central Committee of Mondas, a gestalt of twenty individuals. In relation to their occupations, individual Mondasians held a title before their first names. These included "doctorman" for scientist, "sisterman" for nun or "electroman" for electrician, and eventually, "Cyberman" or "Crewman" for Cyberman (the entire population).
As with the humans of Earth, Mondasians celebrated Christmas, although they dressed their trees for symbolic reasons: the tinsel represented their journey through space; the baubles symbolised planets, and the star at the top represented their home system, Sol. (AUDIO: Spare Parts)
Aging people often had cybernetic enhancements, comparable to pacemakers. They also made use of Cybermats for security and for detecting energy.
One account claimed that the Constructors of Destiny created the Mondasians in an experiment, as a deliberate parallel to humanity, to act as a control in an experiment. (PROSE: The Quantum Archangel) Another identified Mondas as Marinus, and the Mondasians as the descendants of the Voord after they used a Worldshaper for cyber-conversion. (COMIC: The World Shapers) This was contradicted by the Twelfth Doctor, who stated that the Cybermen of Marinus developed independently from those on Mondas. (TV: The Doctor Falls)
At a time when Mondas' orbit was once again decaying, two archaeologists, Korving and Joy, study glyphs which revealed that the Cybermen and Golgoth destroyed each other two thousand years earlier. Believing that Golgoth's son is their last hope for survival, Korving threatened the Lord High Priest of C'iva, the leader of the Cult of C'iva, whom he believed has the answers he sought. However, just then, Mondas broke free of its orbit, and in the cataclysm Joy and the priest were killed. Dying, Korving unknowingly crawled into an old cyber-conversion unit, becoming the first of the new Cybermen. (COMIC: The Dead Heart)
The Twelfth Doctor also encountered a group of Mondasians aboard one of their colony ships. While the majority on the lower floors like floor 1056 had more or less been fully converted in to Cybermen, those living on Floor 0507 and above were still in their natural state. (TV: World Enough and Time/The Doctor Falls)
In an alternate timeline where Rassilon granted a colony of Cybermen at the end of the universe the means to conquer all of history, in the 24th century, the Cybus Cybermen attempted an invasion of Sontar in order to take control of the Sontaran cloning factories and modify them to produce an infinite supply of Mondasians for cyber-conversion. Despite the efforts of the Tenth Doctor, Gabby Gonzalez, Cindy Wu and the Last Great Sontaran War Fleet, the Cybermen succeeded in conquering Sontar; however, these events were erased from existence, along with the rest of the timeline. when, on Gallifrey at the end of the universe, the Twelfth Doctor and a betrayed Rassilon used the regeneration energy harvested by the Cybermen of the Gallifreyan Cyber Fleet from the Time Lords to restore the original timeline via the Eye of Harmony and the Cyberiad's dominance across all of history. (COMIC: Supremacy of the Cybermen)