One of the many unexplained things about Moffat’s era of Doctor Who is what happened to the Cybermen. Due to an apparent mishandling of the metal men early in Moffat’s run, some strange continuity errors have cropped up which baffle fans to this day, and it is all to do with the specific design of the Cybermen that was used in each episode that featured them in the 2010s.
The continuity error surrounds the use of the Cybus Cybermen, a subspecies of Cyberman that originated in a parallel universe during Russell T. Davies’ era as showrunner. These Cybermen, unlike their prime universe counterparts, were more robotic and heavily armoured, and were easily recognisable by their characteristic stomping feet.
Despite originating in a parallel universe, these Cybermen were first seen crossing over into the Doctor’s universe in Doomsday, and were later seen stranded in our universe having fallen back through time to the 1800s in The Next Doctor. These Cybermen used Victorian steam technology to build a rudimentary CyberKing dreadnought, but were stopped by the Tenth Doctor and seemingly destroyed. These Cybermen were seemingly the last surviving Cybus Cybermen, and as far as this Christmas Special is concerned, they were all destroyed when the CyberKing was sucked into the Time Vortex.
That would be it for the Cybus Cybermen, were it not for the fact that they also started inexplicably appearing in early Moffat stories. Series 5’s The Pandorica Opens featured a damaged Cyberman guarding the Underhenge, which was recognisable as a Cybus Cyberman by the distinctive ‘C’ on its chest. Later, other Cybus Cybermen were seen forming part of The Alliance alongside the Daleks, Sontarans and other creatures. How and why these Cybermen were present in Roman times is still unknown.
From Series 6 onward, Steven Moffat and the production team clearly realised that they needed to change the Cybermen in order to distinguish them from the Cybus Cybermen of Russell’s era. Though they would later completely redesign the Cybermen in Series 7, in the meantime the production team simply removed the ‘C’ logo on the chest of the Cybermen and replaced it with a more generic circle-like design. This was allegedly done to establish that these Cybermen were indeed native to our universe, and according to non-narrative sources, the idea was that the Cybus Cybermen had encountered the Cybermen of the Doctor’s universe and the two had merged into one species, explaining the fact that the Cybus design was now used by Cybermen of our universe.
Whatever the reasons, Series 6 saw two appearances of the Cybus-style Cybermen with circular logos. The first was the Twelfth Cyber Legion, the fleet of Cybermen that was terrorised by Rory and the Doctor during their search for Amy Pond. These Cybermen sported the circular logos but the leader featured the distinctive black head and exposed yellow brain of the Cyber-Lord seen in The Next Doctor. The second appearance of the Cybus-style Cybermen was near the end of Series 6 in the episode Closing Time. This episode featured a small group of Cybus-style Cybermen stranded on a crashed spaceship in modern-day London. The Doctor mentions that the ship itself was likely empty for ‘centuries’ until the construction of a nearby power grid restarted the conversion chambers.
These seemingly unconnected Cyberman appearances could, in fact, be connected in more ways than simply featuring the Cybus-style Cybermen. The fact that this specific design is present in all of these appearances suggests that these events are interlinked. Could it be that the Cybermen featured in The Next Doctor are in fact the same as the ones in Closing Time? Or could the prescence of Cybus Cybermen in Roman times eventually lead to a Twelfth Cyber-Legion in the distant future that sported the same design? Perhaps survivors from other Cyber-incursions eventually culminated in the Mondasian Cybermen adopting the Cybus design.
Whatever the reasons, the Cybus model eventually overtook the Mondasian Cybermen, Telosian Cybermen and other disparate Cybermen models to become the definitive Cyberman design, as by the events of Nightmare in Silver both the ‘C’ variant and ‘circle’ variant of Cybus Cybermen are featured as remnants of a recent Cyber-War. This episode also reveals that the Cybermen have evolved beyond the Cybus design, adopting the new look that has endured to this day. Having taken on this new design, the Cybermen of the New Series have been more prominently associated with Mondas as their homeworld, rather than originating from a parallel universe.
However, there are also other examples of Cybermen from parallel universes invading our universe, that may not necessarily be from the same parallel universe as the Cybus Cybermen. These include the Blood of the Cybermen model, sporting a Cyber-face logo instead of the usual ‘C’ but otherwise appearing as Cybus Cybermen, and the ‘Cyber-Reality’ Cybermen that face off against UNIT and the Master in the Big Finish box set UNIT: Cyber-Reality. These Cybermen look and sound like the Cybermen seen from series 7 onwards.
As if that were not complex enough, the final Cyberman story of Moffat’s run further solidifies the idea that the Cybus Cybermen are a natural evolution of the Mondasian Cybermen. During their thousands of years of development during the events of The Doctor Falls, the Cybermen adapt from primitive Mondasian variants to Cybus Cybermen, and later the newer Cyberiad Cybermen. The short story Alit in Underland reveals that an interim stage exists in which the Cybermen appeared as they did in the 1980s, from Earthshock to Silver Nemesis.