Cyber-conversion

Cyber-conversion, also known as cybernetic conversion, (TV: The Invasion) Cybernisation, (PROSE: Attack of the Cybermen) Cyber upgrade, (COMIC: Assimilation²) and, prior to Mondas’ full conversion, processing, (AUDIO: Spare Parts) was the physical and mental re-engineering of victims, often humanoid, into Cybermen.

Several Cyber-subspecies, such as those of Pete's World, the Cyber-Mainframe and the Cyberiad, referred to this as upgrading. A similar process used by the Borg from a parallel universe was called assimilation.

Cybermen of the Doctor's universe
CyberMondan conversion involved the replacement of body parts (including limbs, organs, and vital systems) with artificial components. (TV: Attack of the Cybermen) The Cybermen of the Cyber Legions appeared to simply encase victims inside a Cyber-suit. (TV: Closing Time) Partial conversion, with the victim retaining autonomy and a human identity and body parts, was possible. (TV: The Invasion)

The Cybermen would traverse the universe to find beings to convert, adding to their forces. (TV: Attack of the Cybermen) The Cybermen relied on tubing and external systems to keep the body operating, but over time the amount needed decreased. (TV: The Tenth Planet et al)

Most factions of Cybermen were only capable of converting humans and Mondasians, due to their near-identical physiologies (TV: The Tenth Planet et al), although the Cybermen that attempted to invade Earth via International Electromatics were converted from Isons (AUDIO: The Isos Network), and another group could convert Veridians (AUDIO: Hour of the Cybermen). Some Cybermen could convert non-human lifeforms due to originating from other lifeforms, such as the Voord. (COMIC: The World Shapers) In the far future, one race of Cybermen found themselves facing extinction due to their inability to convert humans after they had spread across the universe and bred with numerous other species; the conversion protocols were keyed to human and Mondasian genetic tissue, although the Eighth Doctor offered to regenerate so they could decipher the Time Lord biomorphic code, and to provide them with his own cellular resequencing template to re-engineer non-human lifeforms into Mondasians, who could then be converted. (COMIC: The Flood) Notably, the Cybermen created by were converted from dead humans, and at least one was converted from a cyborg, the Half-Face Man. (TV: Deep Breath, Dark Water, Death in Heaven)

However, there were a minority of Cybermen capable of converting other species; the Cybermen of the Cyberiad who recovered from the Cyber-Wars were capable of upgrading "almost any living components", and were even capable of converting Time Lords. (TV: Nightmare in Silver) In an alternate timeline created by their allying with Rassilon, the Cyberiad advanced to become capable of upgrading all life, including Time Lords, (COMIC: Supremacy of the Cybermen, Prologue: The Second Doctor, Prologue: The Third Doctor) K9, (COMIC: Prologue: The Fourth Doctor) and Silurians who were converted into Cyber-Silurians. The Cyberiad also began converting animals, the Cyber-Silurians utilising cyber-converted dinosaurs such as pterosaurs and triceratops. These upgrades were later undone when a remorseful Rassilon joined with the Twelfth Doctor to send regeneration energy backwards through the Eye of Harmony, undoing the timeline. (COMIC: Supremacy of the Cybermen) In another alternate timeline, the Cybermen of the Cyber-web assimilated the entire Borg race and proceeded to upgrade both N-Space and the Borg's home universe, converting Judoon, Raxacoricofallapatorians, Klingons and Vulcans. (COMIC: Assimilation²) Following the Fall of the Cyber-Empire, the Cyber-Empire had the technology to upgrade Time Lords. (TV: The Timeless Children)

The main method of cyber-conversion used appeared to be through the use of cyberfication machines (also known as cyber-conversion units), which were machines that would replace the majority of a victim’s body parts with artificial components. These were used by almost all Cybermen, and were featured in almost all locations under cyber-control. (TV: The Tenth Planet et al) Some Cybermen created Cyber-factory, buildings filled with cyberfication machines that were expressely used for mass conversions. On Mondas, these were also known as processing lines (AUDIO: Spare Parts). The patients of the Mondasian colony ship were converted through surgery performed by the surgeon of the hospital on Floor 1056, within the Conversion Theatre. The same process was used to convert Bill Potts into the first Mondasian Cyberman on the ship. (TV: World Enough and Time) The later Cybermen transformed entire apartment blocks into Cyber-Factories before rounding up the humans of the city for mass conversion, with referring to these particular factories as the Cyber Foundries. (TV: The Doctor Falls) Other Cybermen contained cyberfication machines within cyber-ships, and would use them to travel the universe to convert compatible beings. (AUDIO: Sword of Orion, Hour of the Cybermen) A group of Cybermen that attempted an invasion of the Land of Fiction were capable of converting fictional creatures. (AUDIO: Legend of the Cybermen) Cyberfication machines were often also contained within Cyberman bases, such as the Cyber-Control on Telos. (TV: Attack of the Cybermen)

A group of Cybermen who time travelled to Earth in 1939 from the 30th century appeared to use Cybermats in the conversion process. At one point, they attempted to convert a human baby; the result was a horrific fusion between a Cyberman and a Cybermat. (PROSE: Illegal Alien) One group of Cybermen encountered by the Fourth Doctor on Telos possessed Cyber-particles within their hands, allowing them to convert humans merely by touching them. (AUDIO: Return to Telos) A gauntlet discovered by an archaeological team on Catrigan Nova possessed similar conversion capabilities. (PROSE: The Mondas Touch)

created an army of Cybermen by uploading the minds of dead people into “the Nethersphere”, in truth a matrix data slice, then converting the bodies before dowloading the minds back into their Cyber-bodies. This process worked on humans and even appeared to work on the Half-Face Man, despite him being a Clockwork Droid and not a human. These Cybermen were capable of self-destructing to release clouds of Cyber-pollen, that could rain down and upgrade both living and dead humans, no matter how long a human had been dead for. (TV: Deep Breath, Dark Water, Death in Heaven) The "zenith of cyber-conversion", as declared by a Cyber-Leader, was a cyber-conversion planet seen during the Master's Dalek Plan. (TV: The Power of the Doctor)

Cybermen of Pete's World
The Cybermen of Pete's World, instead of replacing body parts, transplanted living brains into metal exoskeletons sustained in a cradle of chemicals and threaded together by an artificial nervous system. The process was extremely painful and took place in a booth where the subject's skull was sliced open by a robotic machine that used knives, lasers and syringes to remove the brain before encasing it in an empty cybernetic helmet.

The Ear Pods created a trance state for the victim, so they were, in a sense, unconscious during the process and unable to feel the pain of being converted due to the Ear Pods having control over the brain's pain receptors. This was the most efficient form of conversion as it took under 60 seconds. Afterwards, the remaining human body was incinerated.

The Cybermen also had an emotional inhibitor placed within them to suppress their humanity because, as the Tenth Doctor put it:

"It's still got a human brain; imagine its reaction if it could see itself. Realise itself inside this thing. They'd go insane."

- The Tenth Doctor

During the Battle of Canary Wharf, the Cybermen, badly needing reinforcements, quickly converted humans into Cybermen using a different method. They encased humans in cybernetic shells by constructing the suit of armour around their body, as with Lisa Hallett. Hallett would have died if her lover, Ianto Jones, had not retrofitted a cyber-conversion unit into life support for her. This form of conversion was excruciating. The subjects were heard screaming as metal was grafted onto their flesh, possibly because the Cybermen had little time to place their victims in a trance state. (TV: Cyberwoman)

The Cybermen also employed a very primitive type of conversion in 1851 when they created the Cybershades using scrap metal and Victorian era human technology. They also invented a method of converting humans into command units for CyberKings by fitting them with a headset that could take control of their brains. The CyberKing was intended as a mass conversion unit, but the command unit Miss Hartigan, aided by the Tenth Doctor, destroyed it before it was put to use. (TV: The Next Doctor)

A Cyberman's exo-skeleton in 102 at Stonehenge displayed the ability to upgrade humans without any external machinery, merely needing to restrain the victim while the Cyberman's faceplate split open at the middle and enveloped the victim's head. The process from here on is unknown, as the only known victim of this process was Amy Pond, who escaped before the process was completed. (TV: The Pandorica Opens) The human that was previously converted seemed to have an upgrade like that during the Battle of Canary Wharf, due to the fact that the Canary Wharf upgrade involved encasing the body inside the suit, (TV: Cyberwoman) while this Cyberman had a severed head in its helmet. (TV: The Pandorica Opens)

As the Cybermen continue to upgrade themselves technologically, it is logical that the methods used to convert victims would itself be constantly modified, thus these differences in conversion should not be considered contradictory.

Cybermen of the Cyber-Mainframe
The Cybermen of the Cyber-Mainframe utilised cyber-conversion methods that were significantly more different and advanced than the Cybermen of both N-Space and Pete's World, although there were a few similarities. (AUDIO: Master of Worlds)

One parallel Earth was ravaged by these Cybermen and its entire human population was captured and turned into a worldwide power station; each human was wired inside a pod that harvested the electricity generated by their body and transmitted through the Cyber-Mainframe to every active Cyber-unit. Kate Stewart speculated these pods would have additionally functioned as cyber-conversion units when necessary. (AUDIO: Telepresence, Code Silver) When the Cyber-Mainframe began converting the Earth of N-Space, the Cybermen oversaw the construction of mass conversion centres across the planet by millions of virtually converted humans. (AUDIO: Master of Worlds)

The dimension seeding protocols that these Cybermen used to begin upgrading other universes involved translocating dimension bridge technology (that resembled virtual reality headsets) to other universes, which, when used by a life-form, would transport their mental avatar to a Cyber-controlled world in another universe. On this world, the Machine would use various Cyber-units to attack a life-form’s mental avatar in order to establish a link to their home universe, allowing a dimension bridge to form, which the Cybermen could then use to travel to, and begin upgrading, the new universe. The lifeform using the dimension bridge technology would undergo a form of cyber-conversion referred to as virtual conversion, where the carrier wave broadcast by the VR headsets would transmit mind control and basic upgrades to the receiver, with full conversion occurring later. (AUDIO: Telepresence, Code Silver) This form of conversion, appearing as metal implants, wires and connections on the victim’s face, could be reversed via means such as a corrosion virus. (AUDIO: Master of Worlds)

However, if a life form were to be disconnected from the dimension bridge technology before their mental avatar could be converted, a delayed form of virtual conversion could occur instead. This began with the Machine reestablishing its link to the user and commencing the transfer of data on the Cybermen to them. Cerebral functioning would then be limited, rendering the victim unconscious, as their connection to the Cyber-Mainframe strengthened. The victim would wake in a dream-like state, where Mechanising Worms would be deployed to begin minimal physical conversion. Eventually the victim would wake up as these upgrades were installed, eventually leading to full virtual conversion and the formation of a dimension bridge. (AUDIO: Telepresence)

Shortly after her virtual conversion, Osgood underwent a further stage of upgrading referred to by one Cyber-Controller as a “cranial upgrade”. This appeared to be an extension of the dimension bridge technology’s mind control capabilities, as Osgood was granted full access to the Cyber-Mainframe despite not being fully converted. In this state, she retained her original personality but was loyal to the Cybermen and the "Cyber-Ideal" instead of UNIT, and became the second-in-command of the Cybermen’s invasion of the Earth of N-Space. She initially experienced frequent mental pain that nearly killed her due to the sheer amount of information that she received from the Cyber-Mainframe, (AUDIO: Code Silver) but was cured of this after she "received a brainstorm from Cyber-Control across every dimension" in response to the arrival of. (AUDIO: Master of Worlds)

Mobile conversion units were large conversion machines resembling giant metal spiders utilised as part of the dimension seeding process once a link to a new universe had been established. They were deployed in conjunction with a tiny patrol of around ten Cybermen, being used to perform high-speed conversions so as to boost the Cybermen’s numbers without risking a loss of dozens of Cyber-units. Conversions through this method were completed in about five seconds. However, they appeared unable to convert Autons or lifeforms with similar biologies, as one registered Josh Carter as human based on his speech alone, and another attempted to convert him (AUDIO: Code Silver) only to be hijacked by him and used as a means of transportation, and later as a weapon against other Cybermen. Additionally, Osgood was able to enhance one mobile conversion unit with the ability to convert Time Lords in a bid to upgrade the Master, by retaining his higher brain capacity and the symbiotic link to his TARDIS; however, she underestimated his intelligence, resulting in the “Cyber-Master” destroying the Cybermen and stopping their invasion of the Earth of N-Space. (AUDIO: Master of Worlds)

Mechanising Worms were capable of inflicting basic upgrades by biting a target, making them somewhat similar to Cybermites, and large swarms could be released by deceased Cybermen to fully convert anyone nearby to replace the lost unit. (AUDIO: Code Silver) They were also used by the Machine to perform basic upgrades on humans and dimension bridge avatars as part of the dimension seeding process. On one parallel Earth, a wild mutated dog underwent conversion after getting too close to a much larger Mechanising Worm. At least one flock of pigeons was cyber-converted as well, though the method used was unknown. (AUDIO: Telepresence)

In addition, both Osgood and the Master were able to modify existing cyber-technology to create further advanced conversion methods. Osgood adapted the virtual reality app developed by the Auctioneers to broadcast the mind control signal of the dimension bridge technology through mobile phones instead of the headsets; by setting up the app as a free automatic download, millions of people were virtually converted in seconds. (AUDIO: Code Silver) However, the app could also be broadcast to have the opposite effect, erasing the VR upgrades instead. Additionally, the Master used a signal emitter to broadcast an amplified version of the VR headsets‘ carrier waves to fully convert a patrol of guards in one of the Auctioneer bases, causing metal implants to appear all over their bodies, converting them in seconds. (AUDIO: Master of Worlds)

Cybermen of Mondas
The first known Cybermen, if not the first, Zheng was converted as part of the Mondasian effort to steer their planet away from the destructive cherrybowl nebula, and back to Sol, with a propulsion system on the surface. Like other early Cybermen, Zheng retained his name, as Cybermen were regarded as still being individuals by their creators. Unlike other early Cybermen, however, Zheng was not affected by organ rejection, a problem which affected the Cybermen until they learnt of a way of avoiding it by scanning and copying part of the physiology of the Fifth Doctor, specifically a lobe in his brain that dealt with all bodily functions. Before this, however, he was unique in surviving for so long, and he was made Cyber-commander. Zheng was more resilient than other Cybermen, being able to survive being shot by another Cyberman on the orders of the first Cyber-Planner, (AUDIO: Spare Parts) and still functioned well after all Mondasians were converted. (AUDIO: The Reaping)

The Mondasien Chang Twins joined the surface work crews, and were converted into Cybermen. (AUDIO: Spare Parts) Mondasien teenager Eric Krailford either volunteered to join or was drafted into the surface work teams, and was converted. (AUDIO: Spare Parts) As a Cyberman, he retained part of his name, and became Krail. In 1986, he led the first force of Cybermen to land on Earth in the occupation of Snowcap base, and was killed by General Cutler. (TV: The Tenth Planet)

After being drafted by the Mondasian government to work on the propulsion system, Yvonne Hartley was mostly converted. Conversion was stopped by loss of power caused by proximity to the cherrybowl nebula, and Yvonne wandered back to her home, due to her pre-conversion desire for her Father to see her 'uniform'. Enough of her individuality survived for her to recognise her Father and her pet Cybernetic bird. When power was restored, her conversion continued automatically. Away from the hospital used for conversions, the process killed her. (AUDIO: Spare Parts)

Sisterman Constant was originally responsible for draughting Mondasians for conversion, but was injured when a partially converted Cyberman tried to force her to divulge their purpose. Cyber-commander Zheng shot the Cyberman, and, noting that her scapula was fractured, sent both the Cyberman he had shot and Constant to be repaired. Despite her protests, Constant was converted, and as a Cyberman advocated full conversion of Mondas. (AUDIO: Spare Parts)

Thomas Dodd, the owner of a store selling replacement organs and limbs, was captured by the Cybermen while trying to help the Fifth Doctor. He was converted, becoming the first Cyberman to be augmented with an additional lobe, based on that found in the Doctor's brain, that dealt with bodily functions and prevented organ rejection. (AUDIO: Spare Parts) Toberman was Partially converted on Telos with his right arm replaced. He regained his humanity and attacked the Cyber-Controller. He gave his life to close doors of the Cybermen's tombs (TV: The Tomb of the Cybermen)

Bates and Stratton, when Cyber-converted, found it failed at an early stage after their limbs had been replaced by mechanical equivalents. They put to work on the surface of Telos with similar such failures. Lytton was Partially converted cyber on Telos, still incomplete at the time of his death. Others notably converted were Bill and David. (TV: Attack of the Cybermen)

In a divergent timeline, Evelyn Smythe, Nicola Savage, Ricky Allen, Ryan Carey and David Isherwood were all partially converted. Reece Goddard became a skin drone. (WC: Real Time, AUDIO: Real Time)

Tobias Vaughn suffered partial cyber-conversion, retaining just his head and therefore his own thoughts. (TV: The Invasion)

Jason Kane was nearly converted after being manipulated by Irving Braxiatel. Before the conversion was complete, however, Bernice Summerfield used the energy in the Crystal of Cantus to defeat the cybermen, reversing the conversion. (AUDIO: The Crystal of Cantus)

Webley was partially converted by cyber mites. He retained most of his body and, based on speech, some emotions as well. Artie Maitland and Angie Maitland suffered partial conversion by Cybermites, who intended to take advantage of their imagination. The conversion was later reversed. A pair of soldiers were partially converted while in combat with a Cyberman. The Eleventh Doctor was partially converted into a Cyber-Planner, splitting his mind into two halves; one himself, and the other the self-titled Mr Clever. Using a chess game to buy himself time, the Doctor eventually managed to destroy his cyber-implants by using his sonic screwdriver to magnify a hand pulse, freeing his mind. (TV: Nightmare in Silver)

Bill Potts, after being mortally wounded, was taken to a hospital on a Mondasian colony ship and was granted a cybernetic heart then fully converted into a CyberMondan after ten years. Prior to her full conversion, she was unable to survive if she did not remain in the hospital. (TV: World Enough and Time)

Cybermen of Pete's World
John Lumic was converted into a Cyber-Controller, while numerous others such as Sally Phelan and Jackie Tyler were converted into regular Cybermen. (TV: The Age of Steel)

Yvonne Hartman, a Torchwood Institute administrator, was converted. She retained her free will though, killing several Cybermen before her death. (TV: Doomsday) Another Torchwood employee, Lisa Hallett, the lover of Ianto Jones, was partially cyber-converted (TV: Cyberwoman)

Mercy Hartigan was the CyberKing command unit. Miss Hartigan refused to be converted to a standard Cyberman and took control of the Cybermen which landed in 1851. The Cybermen, however, had slowly set a plan in motion that would eventually make Miss Hartigan both a convert and a leader. (TV: The Next Doctor)

Cybermen of the Cyber Legions
Several people (namely Shona, George, Atif Ghosh and Sheila Clark) were converted by the Cybermen of a crashed ship as they attempted to find a suitable Cybercontroller. They eventually chose Craig Owens but the conversion failed when Craig's paternal instincts were triggered by his son's crying. (TV: Closing Time)

Cybermen created by Missy
Missy transformed the dead corpses of millions of humans into Cybermen, such as Alistair Gordon Lethbridge-Stewart, Danny Pink and Skarosa. They were eventually destroyed when Danny detonated all of them to stop Missy's plans, save for Lethbridge-Stewart, who shot Missy personally before being saluted by the Twelfth Doctor. (TV: Death in Heaven)

Behind the scenes
In The Fact of Fiction in DWM 585 by Alan Barnes, a potential explanation is given for the sparks seen during Yvonne Hartman's cyber-conversion in Doomsday. As brain matter could not literally be welded to the Cyberman exoskeleton, as previously explained in Rise of the Cybermen, Barnes reasons that the brain may in fact be fitted into bespoke steel cases, precision-tooled to fit differently sized human cerebra — as the size of human brains vary person to person — which in turn is welded to the Cyberman head.