Mondasians were, according to the Eighth Doctor, one of only two species — along with humans — on which the cyber-conversion process worked. Indeed, the Doctor further described them as humanity's "closest cousins". (DWM: The Flood) Also called Mondans, (NA: Iceberg) Mondasians were natives of the planet Mondas who eventually created the technology that gave rise to the subspecies known as Cybermen.
Etymology
Amongst Cybermen, the term Mondan has a peculiar meaning. According to at least one account, it referred to those Cybermen who stayed on Mondas and were philosophically opposed to the Faction. (NA: 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, is this narrower sense of the word, Mondans were the form of Cybermen that the First Doctor encountered shortly before his regeneration. (DW: 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 species 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. (BFA: Kingdom of Silver)
Culture
Mondas was ruled by the Committee, 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 "Workman" for Cyberman (Mondas) (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 representing planets, and the star at the top representing their home system, Sol. (BFA: Spare Parts)
Technology
For a reason the Doctor was unclear of (DW: Attack of the Cybermen), Mondas was equipped with a propulsion system that could drive the planet out of its orbit.
Aging people often had cybernetic enhancements, comparable to pacemakers. They also made use of cybermats for security and for detecting energy.
Their cities were domed, the surface of their world considered inhospitable. However, fully converted Mondans had sufficient life-support to perform work on the surface. (BFA: Spare Parts)
History
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 a experiment. (PDA: The Quantum Archangel) Another identified Mondas as Marinus, and the Mondasians as the descendants of the Marinusians after the Voord used a World Shaper for cyber-conversion. (DWM: The World Shapers)
At the time that the Fifth Doctor and Nyssa encountered it, Mondasians society was comparable to 1950s Great Britain before the entire population was fully converted. (BFA: Spare Parts)