Unbound Master

A version of the Master from a parallel universe was a Time Lord exiled on Earth.

Exiled on Earth
Having had his TARDIS placed beyond his reach, the Master spent his time stuck on Earth through the 1970s right through to 1997 when the Doctor was sent to Earth by the Time Lords. He worked for the United Nations and then defected to China after being sent there to assist against alien parasites. He turned the parasites into a way of brainwashing political prisoners into zombie-like soldiers organised into Ke Le Divisions. (AUDIO: Sympathy for the Devil)

Fleeing to Hong Kong
Losing favour with the new Chinese government in 1997, he fled to Hong Kong to allegedly defect back to the West. He regenerated when he crashed an experimental cloaked plane on Hong Kong, and tried to gain the last of the parasites. He was rescued by Adam, but the Master then proceeded to kill and steal his garments, including a Union Jack tie. China intended to wash their hands of the Ke Le Divisions by destroying the other parasites. The Master realised this would cause the Divisions to go insane under the weight of their returned memories; with the last parasite, he intended to seize control of the Divisions and the country.

When the Doctor arrived, the Master showed a genuine bitterness at having to live on an Earth where the Doctor hadn't been present for thirty years; he brought up scores of atrocities that the Doctor had failed to stop, accusing him of letting entire cultures and races die from missing the big picture, choosing the wrong sides, and simply not turning up. During his tirade, he let slip he had been trapped on Earth, leading the Doctor to realise he was desperate to escape. Eventually, he agreed to help the Doctor and UNIT destroy the last parasite - allowing them to believe nothing bad would happen - in return for being taken off Earth in the TARDIS, while secretly planning to betray everyone. Unfortunately for him, the Doctor had anticipated this and tricked the Master into being left in Hong Kong as the TARDIS departed.

In a desperate attempt to be evacuated from the city, he admitted to UNIT's Colonel Brimmicombe-Wood that the Ke Le Divisions would go insane once the last parasite was destroyed. By this point it was too late, and the Master was last heard giggling as the Divisions massacred Hong Kong. (AUDIO: Sympathy for the Devil)

The War
Having escaped Earth, the Master fought alongside the Doctor in a great war against some other enemy, with the natives of the planet Tramatz being a key player in one side of the conflict. Towards the end of the war, the Master had acquired a weapon that would destroy the enemy at the cost of essentially destroying the universe as well, with the Doctor fleeing the conflict in the hope that the Master would be unable to activate the weapon without him. However, the Master used the weapon, leaving the universe faced with near-imminent collapse, requiring the Doctor to sell most of his memories (including the ones involving the Master) to try and power a means of delaying this collapse. (AUDIO: The Emporium At The End)

The Doctor heard his voice when he was captured by the Library. (AUDIO: The Library in the Body)

He posed as the Manager of the shop at the Gateway to the universe; in this position, he created a lottery which had a prize to get out of this universe. People could pay for partecipation either with their goods, or with their memories. When the Doctor showed up with a group of survivors and Bernice Summerfield, the Master immediately saw that she didn't belong to his universe and paid attention to her. He arrested her for shoplifting, and took the chance to invite her to dinner. He told her he found a way to save everyone, which included sending Benny back to her universe in order to create a permanent bridge between the two universes, while he would stay on this side to keep the bridge stable from both sides. Benny was persuaded and agreed to do it, but before she could do it, the amnesiac Doctor regained enough of his memory to suspect the Master of a trap and shut down the portal. He explained to Benny and everyone else that, in fact, the Master was using the energy of the people in the universe to create the illusion that the universe was dying ahead of schedule so that he could guarantee his own escape, and that his alleged portal just disintegrated those who used it to act as a power source for the Master's planned escape later on. Benny believed the Doctor, and asked the Master to pass first through the portal; his refusal to do so proved the truth of the Doctor's words. The Master was then subsequently grabbed by the people present, thrown into the portal himself and apparently killed. (AUDIO: The Emporium At The End)

The Master escaped death once again, and began to plot to replace the Doctor as President of the Universe. This played into the Doctor's hands, as he too planned for the Master to take over from him, sabotaging his own leadership to make the change seem natural. Using the equations the Doctor had devised from the Apocalypse Clock to save the universe, the Master triggered these calculations in the belief that he would awaken the Great Old Ones who had originally created the equations to act as his servants, but as they prepared to feed on everyone in the safe zone created by the equations, the Doctor used the energy channeled by the equations to power his own attempt to take Benny back to her universe and send the Old Ones back to their world. The Doctor believed that the Master would make a good president, as he would be kept in check by the Mother Superior. He also recognised that the Master wouldn't like the bureaucracy of the position, as the Master inherited the Parliament the Doctor had created which he had previously admitted was not the kind of government he would have liked. (AUDIO: The True Saviour of the Universe)

Escape into N-Space
After some time, the Master became the last being alive in the universe, at which point he sent out an inter-dimensional distress call. After around 10000 years, the call was answered by the Daleks from N-Space, who had sought his assistance in stopping from their universe from interfering with their history. (AUDIO: Shockwave)

In N-space, the Master helped the Daleks in their plan to stop, visiting many Gallifreys in an attempt to find the progenitor of the time disturbances. (AUDIO: Shockwave)

Eventually, after many failed attempts to destroy the progenitor, the Master and the Daleks visited the "War" Master on Skaro to sow discontent in the Daleks, and unease in the "War" Master, eventually succeding. The "War" Master intially did not recognise the alternate Master's appearance as one of his other selves, until he revaled himself. The Master told his alternate self that in order to restore the original timeline, they had to come back to a point in time when they could forbid this timeline from happening. The "War" Master agreed to help, and brought them to the time when he connected with a telepathic circuit his TARDIS to Crazlus, a Gallifreyan scientist, before sending him to enter the CIA and raise in a position of power where he could help him in his plan.

The "War" Master contacted his past self, and tricked him into bringing Crazlus to them, so that the Dalek Time Strategist could kill him, thus reverting the timeline to its original course. As a result of this, though, the Artron energy connecting the alternate Master to this reality began to falter, threatening to send him back to his universe. The "War" Master saved him by bringing him into his TARDIS, while the Daleks were trying to capture them, and the alternate Master managed to stabilize himself enough to escape into a wormhole when the Daleks hit the "War" Master's TARDIS, thus escaping capture. (AUDIO: He Who Wins)

Schemes in N-Space
He eventually met Kamelion, and decided to invade Gallifrey. (WC: Masterful social media-only exclusive scene)

Behind the scenes

 * The character is called "Ke Le" on the Sympathy for the Devil CD case.
 * This version of the Master was played by Mark Gatiss, using the anagrammatic pseudonym "Sam Kisgart". This was a reference to the use of anagrams to hide Anthony Ainley's appearances in several stories in the 1980s.
 * Mark Gatiss also portrayed an incarnation of the Doctor who appears in the comedy sketch The Web of Caves. Along with Derek Jacobi, this makes Gatiss one of only two actors to have portrayed both the Master and the Doctor in licensed appearances.
 * Jonathan Clements, author of Sympathy for the Devil, voiced the dying previous incarnation of the "Exiled" Master, who was intended to be Roger Delgado's Master.