Ashad

A partially Cyber-converted human, originally known as Ashad, came to be known as the Lone Cyberman when he re-lit the flame of a lost Cyber-Empire. Though at first he was rejected, when offering himself up for conversion, Ashad later played a key role in the re-ascension of the Cybermen, following their near-annihilation in the Cyber-Wars.

Though he maintained much of his human appearance, as well as temperament, Ashad despised his own kind throughout. Loyal to the cause he believed in, and filled with hatred, the Lone Cyberman sought to restore the Empire to its former glory, and then to extinguish all life, beyond the race he revered.

After intending to destroy all organic life in the universe, Ashad was killed by with the Tissue Compression Eliminator in order to gain access to the Cyberium while the Doctor and her companions blew up Ashad's Cybercarrier and its army of Cybermen, foiling his plans. His remains and death particle was subsequently used by Ko Sharmus to destroy the CyberMasters. (TV: The Timeless Children)

Origin
Originally human, (TV: Ascension of the Cybermen) Ashad had multiple children before undergoing cyber-conversion, transforming him into a Cyberman. He did not have an emotional inhibitor, stating he "[did] not need to be stabilised". As he recalled to the Thirteenth Doctor and Mary Shelley, his children joined the resistance and so he slit their throats. (TV: The Haunting of Villa Diodati)

Ashad offered himself up to join the ranks of the Cybermen, but they rejected him. Regarding himself as a "believer", however, he stayed committed to the cause. After the Cyber-Army was all but lost, he took it upon himself to revive the Empire, as their champion. (TV: Ascension of the Cybermen)

Forewarning
Captain Jack Harkness once tried to contact the Doctor to warn him and "beware of the Lone Cyberman" and to not give it what it wants. However, he got hold of Ryan Sinclair, Yasmin Khan and Graham O'Brien instead, initially believing them to be the new Doctor. When he was told that he was she, he told them to warn her instead and tell her about a fallen empire. (TV: Fugitive of the Judoon)

Searching for the Cyberium
Ashad travelled back in time to 1816 to attempt to extract the Cyberium, the database of Cyberman history, from Percy Shelley. The Thirteenth Doctor absorbed it herself, knowing Shelley's death would alter the future. However when Ashad threatened to tear reality by summoning his ship, she relinquished the Cyberium to him, knowingly ignoring Captain Jack's warning but deciding she would rather confront the Cybermen in the future than change the course of history by having the Earth destroyed in 1816. After taking the Cyberium, Ashad disappeared. (TV: The Haunting of Villa Diodati)

Restoring the Cybermen
After returning to his own timeline, Ashad found two Cyberguards to accompany him and two cyber shuttles to reach the refuge planet. After arriving, he launched a attack of Cyber Drones on the Doctor and her companions

Alliance with the Master
After Ashad reached the Planet of the Boundary, he realised that humans were aboard the Cybercarrier, though they were able to evade his search by hiding in Cyberarmour. Ashad was subsequently contacted by who offered him an alliance and the planet of Gallifrey. Accepting, Ashad took his ship to Gallifrey through the Boundary, though he left behind death squads to kill the humans still on the planet's surface.

In the Matrix chamber, Ashad met with the Master, though he was alarmed to see the Doctor in a paralysis field. The Master reassured Ashad who explained that his goal was to upgrade the Cybermen to become a purely robotic race before using the death particle created for him by the Cyberium to wipe out all life in the universe. Disgusted by the idea of purely robotic creatures, the Master instead suggested using the Cybercarrier's cyber conversion chambers to transform the deceased Time Lords into Cybermen, an idea that Ashad found appealing.

As the Master and Ashad examined the chambers aboard the carrier, the Master questioned Ashad about the Cyberium and attempted to get it to leave Ashad in favour of him. Ashad furiously told the Master that the Cyberium would never leave him as long as Ashad was still alive. In response, the Master used his Tissue Compression Eliminator to shrink the Lone Cyberman, killing him and releasing the Cyberium. (TV: The Timeless Children)

Post-mortem
The Master, though dismayed that Ashad's death didn't detonate the death particle, was able to convince the Cyberium to take him as its new host and left Ashad's shrunken remains on the floor of the carrier.

Ashad's shrunken body was found by the Doctor as she and her companions destroyed the Cybercarrier and the Cyber-Army aboard it, foiling Ashad's plan to rekindle the Cyber-Empire. Contacted by the Master who had created an army of CyberMasters instead, the Doctor attached Ashad to an explosive in order to sacrifice herself to detonate the death particle and end the Master and his army. However, Ko Sharmus decided to sacrifice himself instead to make up for causing the problem in the first place by sending the Cyberium somewhere that Ashad could eventually find it. In his last moments, Ko Sharmus detonated the bomb, obliterating Ashad's remains and detonating the death particle which wiped out all organic life on Gallifrey, the Master and his army presumably included. (TV: The Timeless Children)

Personality
Due to his lack of an emotional inhibitor, Ashad was able to express and understand emotions and even tended towards anger. Despite this, he lacked mercy or remorse, being completely loyal to the Cybermen and revealing he killed his own children for joining the resistance. He also knew how to manipulate emotions, as shown when he taunted Mary Shelley about sparing her son not out of pity, but because he was unsuitable for conversion, and when he blackmailed the Doctor into handing over the Cyberium or he'd tear reality by summoning the ship. (TV: The Haunting of Villa Diodati)

Appearance
Having undergone a partial cyber-conversion, Ashad's human body was housed in an incomplete, weathered Cyber-suit resembling those associated with the Cyberiad, (TV: Nightmare in Silver) but with a left arm resembling those of both the planet Mondas and the Mondasian colony ship's first Cybermen, (TV: The Tenth Planet, World Enough and Time, The Doctor Falls) lower legs matching the Cybus-style model assocaited with the Cyber Legions, (TV: Rise of the Cybermen, A Good Man Goes to War) and a unique Cyber-helmet with an incomplete faceplate that exposed the left side of his face. He wielded a functional Cyber wrist blaster, though its energy could be drained by time hopping.

Similar to the converted Alistair Gordon Lethbridge-Stewart, Ashad's side handles were mostly silver but with black corners.

Most notably, Ashad lacked an emotional inhibitor. Being a willing recruit to the Cyber-Empire, he mostly retained control of himself, claiming to the Thirteenth Doctor that he did not need to be stabilised, though he was prone to emotional outbursts. (TV: The Haunting of Villa Diodati, Ascension of the Cybermen)

Behind the scenes

 * Ashad's Cyber-body being a combination of several Cyberman models evokes the monster in Mary Shelley's Frankenstein.