Cyborg

Cyborgs are characters who have some parts or their full body been changed to cybernetic parts to improve their performance and abilities. This is done through a process commonly referred to as roboticization (not necessarily to be confused with the process of the same name from Sonic the Hedgehog) or automation.

Known Cyborgs

Canon

Sektor (unit LK-9T9): Was the first to undergo this process of automation, and he would prove to be their biggest success. The Lin Kuei programmed the cyborgs to do their bidding, and Sektor's main objective was to seek out and kill Sub-Zero, who left the clan after refusing to be transformed into a machine. Sektor was devoid of a soul, lost all human emotions, and has never succeeded in his mission.
Cyrax (unit LK-4D4): Was the second Lin Kuei warrior who was turned into a cyborg. However, Cyrax was captured by Sub-Zero, reprogrammed, and permanently malfunctioned. He was then found by Sonya Blade and Jax Briggs, and was partially returned to his human state. In gratitude, Cyrax joined the Special Forces.
Smoke (unit LK-7T2): Was the third and only member of the clan to forcefully transform into a cyborg. After returning from a mission, he and Sub-Zero learned of the Lin Kuei's plans to transform their members into robots. The two fled; Sub-Zero escaped, but Smoke was captured and forced to become a cyborg. Although Sub-Zero was eventually able to help him rediscover his humanity and restore him to the side of good, he was later captured in Outworld by Shao Kahn's army. Hopelessly imprisoned, he chose to shut himself down. Afterwards, Smoke was found by Noob Saibot and reactivated, along with some tampering of his machinery. The two would form a team called Noob-Smoke. Smoke was torn between serving his new master and searching for his lost humanity. As of the Battle of Armageddon, he appears to have been once again restored to the side of good by Sub-Zero.
Sub-Zero (unit LK-52O): Replaced Smoke in Mortal Kombat (2011). In this timeline, Smoke was saved, and Sub-Zero was turned into a cyborg instead. Cyber Sub-Zero is much like his human counterpart. He regained his soul almost right after automation when he engaged Kabal in kombat, and helped the Earthrealm Warriors. He was later killed by Sindel, with his soul afterwards being one of the many claimed by Quan Chi. Unlike the other Cyborgs, Cyber Sub-Zero's blood is blue instead of red; there is no in-game explanation for why that is, but the assumption can be made that it is likely some kind of refrigerant.
Jax Briggs: When his arms were replaced with robotic ones after his original organic arms were torn off by Ermac, Jax became a cyborg, although he is not a cyborg ninja.
Kano: A Black Dragon criminal and mercenary, who has a metal plate over the right half of his face with a mechanical eye, capable of emitting laser beams.
Hsu Hao: A Red Dragon spy, who has a pulsating cybernetic implant that also enhances his strength instead of a heart.
Kabal: A Black Dragon criminal-turned-police officer, fitted with a cybernetic life support system after he was burned alive by Kintaro.

Non-Canon

Hydro: He appeared in Mortal Kombat: Legacy, as a test presentation for Cyrax and Sektor. They completed their mission and killed him.

Unknown

Unit 5: A black cyborg ninja, but is essentially a darkened version of Cyrax. Yet when his armor is appropriated by Reptile, it is essentially a green version of Cyber Sub-Zero.

It has never been clear as to how mechanical the automations truly are. In Mortal Kombat 3, a damaged cyborg sparks and the skeleton is revealed. The skeleton is almost completely mechanical, aside from the rib cage and skull. The rest of the body is filled with odd mechanical parts and wires. This was about as complex as the cyborgs were at the time. In Mortal Kombat Gold, it was revealed that the cyborgs wore helmets and retained their faces underneath; Cyrax's alternate outfit and ending revealed this. His face had several implants on the eye and chin (which were removed in Mortal Kombat: Deadly Alliance). Although Cyrax claimed to be human again in his Gold ending, he is still clearly mechanical as demonstrated by his abilities in Deadly Alliance, although this could be merely a figure of speech referring to regaining his humanity. In Mortal Kombat: Deception, however, Smoke's appearance does not allow the possibility of retaining flesh. This is most likely due to being remodeled from the nanomachines in his body. Sektor's level of cyberization has never been elaborated on, although Cyrax's Armageddon ending implies that it is possible for him to return to his human form. The X-Ray Moves in Mortal Kombat (2011) reveal that the Lin Kuei cyborgs retain their biological skeleton and organs.

In Mortal Kombat: Tournament Edition, it is revealed that Sektor eventually creates his own clan of cybernetic warriors called the Tekunin. They are featured prominently in Mortal Kombat: Armageddon's Konquest mode, where Sektor captures the protagonist Taven and brings him aboard his Tekunin warship until later he and his clan were attacked by Sonya Blade and the Special Forces, thus enabled Taven to escaped his captors.

Jax replaced his arms with mechanical ones in Deception and after his bout with Ermac in MK (2011).

Behind the scenes

According to John Tobias, the cyberninjas started with John wanting to do a haunted armor, somebody else had the idea to making it a robot. Although wasn't convincing at first, the idea had an opportunity when John used the part about the Lin Kuei using advanced tech from the MKII official comic to tie the robots as assassins for the Lin Kuei. One of the inspirations of the entire Sektor/Cyrax subplot (a.k.a Cyber Initiative) was the Tinman from The Wizard of Oz. Instead of full robots, they were former human members from the Lin Kuei and, like the Tinman, they longed to be human again (like Cyrax and Smoke in the first timeline).^[1]

The outfits used for the cyborg ninjas in MK3 were actually a mix of BMX motocross gear, hockey protection, duct tape, and rubber tubing with some custom alterations made for the ninja part.^[2] The only completely original element used was the helmet itself. Jax's cybernetic arms were actually painted on the actor to give them a more fluid, high tech feel.

Trivia

On June 22nd, 2011, the first Compatibility Pack for Mortal Kombat (2011) was released as a free DLC patch for those who are not yet able to purchase the new DLC character Skarlet. Included in this pack are the MK3 skins for Sektor and Cyrax, making these costumes the first free character-related DLC. Cyber Sub-Zero also later received a MK3 style costume with the Freddy Krueger compatibility pack, making him the only non-klassic character to receive a Klassic Costume.
By viewing the battle damage models, one can discover that the head and brain are still somewhat intact through the shell, although small cybernetic implants have been installed as well as their eyeballs being replaced by robotic ones.
The only trait all the cyborgs in the Mortal Kombat series share are their "dreads", which are really just cables.
The cyborgs loosley resemble the Yautja alien race from the Predator science fiction/action franchise.