Played by William Hughes, Milo Parker and other actors
This Master grew up on Gallifrey alongside the Doctor, attending the academy together. During this time of their lives, they were very close friends. As part of his initiation, the young Master was eventually taken to the Untempered Schism, a gap in the fabric of reality that all Gallifreyan children were taken to in the Time Lord academy. The Master looked into it and heard what he would go on to describe as the drums, a repeating sound that locked its place into his mind and ended up driving him insane. In the audio drama Masterful, this Master was brought into the future with many of his other selves by the Saxon Master as part of his plan to steal the lives of his past selves, which would create a paradox he believed he could sustain. As an adult he also encountered the First, Second and Seventh Doctors. Nyssa seemed to encounter a hallucination of this Master in The Toy.
Played by Roger Delgado
This Master was the first Master to have ever appeared on-screen, arriving on Earth in the 20th century and trying to invade it with the help of the Nestenes and their Autons. It was during this encounter that he met the Third Doctor, who had been exiled to Earth by the Time Lords. Ruining his TARDIS, the Doctor stranded the Master on Earth with him and the two would frequently do battle with one another. The Master was eventually captured and imprisoned, but escaped and repaired his TARDIS. His final encounter with the Doctor saw him trying to invoke a galactic war between the humans and Draconians using a device that caused the two species to see Ogrons as the other. The Doctor thwarted this plan but the Master managed to escape. It was planned for this Master to make another appearance after this, in which he would have sacrificed himself to save the Doctor, but it did not happen due to Roger Delgado's unfortunate passing following a car accident. Instead, the character was briefly retired from the series.
Played by Norman Stanley
This disguise was worn by the Master in Terror of the Autons, where he used it to pose as a telephone mechanic to gain access to UNIT headquarters. He spoke to Mike Yates inside of the Doctor's lab while installing a new plastic telephone cord into the room, hoping it would later come to life and strangle the Doctor. This plan almost succeeded but the Brigadier arrived just in time to save the Doctor by cutting the cord in half and severing its connection. This story marks the only time in the series where one of the Master's disguises have been played by a separate actor, technically making Norman Stanley the second on-screen actor to have ever played the Master.
Played by Peter Pratt and Geoffrey Beevers
The Fourth Doctor first met the Master on Gallifrey in his final incarnation, where he had attempted to regenerate once again and had horribly burned himself as a result, leaving him in a very decayed almost skeletal state. In their first encounter, the Master had lured the Doctor to Gallifrey in an attempt to frame him for assassinating the president, hoping to steal the Sash of Rassilon for himself so that he could open the Eye of Harmony on Gallifrey and use its power to restore himself. While the Master did briefly open the Eye, the Doctor successfully closed it and stopped him from harvesting all of its power. However, it had somewhat restored the Master to a less crispier state, as seen when the Doctor encountered him a second time on Traken. Here, the Master was still intent on restoring his body, hoping to use his TARDIS to become the new Keeper of Traken, which would allow him to access Traken's power and restore himself to how he once was. Yet again, he almost succeeded but was stopped by the Doctor, Nyssa and Adric. However, the Master had taken in enough of Traken's power to allow him to hijack the body of Nyssa's father, Tremas, claiming it for himself. Every time his stolen bodies depleted, the Master reverted back into this decayed form until finally becoming a normal Time Lord again (read the Dominion Master).
Played by Anthony Ainley
Having successfully hijacked a new body, this Master was technically the same incarnation that had appeared beforehand, albeit in a new body. He kept this body for quite a long time, encountering the Fourth, Fifth, Sixth and Seventh Doctors on many different occasions. Their first encounter saw him attempting to destroy Logopolis, which would have resulted in the state of the universe being thrown into unbalance. This encounter also led to the Fourth Doctor's regeneration, though he was able to defeat the Master and stop him from wiping out the universe. Their last encounter on-screen saw the Master stranded on the planet of the Cheetah People, where he had contracted the Cheetah virus. This virus was causing him to become more and more feral, though he managed to keep it under control and retained his overall personality. Finally escaping to Earth without his own TARDIS, he tried to steal the Doctor's for himself. The Doctor soon confronted them and the two fought in combat on the planet of the Cheetah People. The Doctor refused to fight, however, and was sent back to Perivale in the 1980s, while the Master was left behind on the planet with his fate left unclear. It's likely that this incarnation could have made another appearance if the series had not been cancelled and put on hiatus after this story.
Keith Potter Disguise
Played by Chris Finney
This disguise was an avatar controlled by the Tremas Master from within the safety of his TARDIS in the audio drama The End of the Line. He planned to dominate the dimensional nexus owned by the Parallel Sect at the same time the Valeyard planned to use it to heal himself, but was defeated by the Sixth Doctor and Constance. The Valeyard then threatened the Master, making him leave both the Doctor and the nexus alone.
Played by Gordon Tipple
Very briefly appearing at the beginning of the 1996 TV movie, this incarnation of the Master was put on trial by the Daleks and exterminated. It isn't made clear in the story if this incarnation is meant to be the same one that was played by Anthony Ainley, though his face is blacked out and his eyes are shown to still be infected with the Cheetah virus. Originally, the opening of the movie was to be narrated by Gordon Tipple, but his narration was replaced with narration from Paul McGann not longer after he recorded it.
Played by Eric Roberts
Now in a human body, the Master sought to properly restore himself once again, this time wanting to take the Doctor's regenerations for himself after having used up all of his own. At first finding it hard to use this body, the Master soon adjusted to it and enlisted the help of Chang Lee, a street thug who had stolen the Doctor's possessions and found his way into the TARDIS, lying to him and claiming that the Doctor had stolen his body. Together, they tried to hunt down the newly regenerated Eighth Doctor and open the Eye of Harmony inside the Doctor's TARDIS. The Master's plan almost succeeded, having opened the Eye and beginning the process of stealing the Doctor's regenerations, but this was temporarily stopped after the Doctor's new companion, Grace, put the TARDIS into a temporal orbit. Enraged, the Master attacked the Doctor but fell into the Eye of Harmony, being dragged into it and sealed inside after it closed. He escaped from this prison several times, meeting characters such as River Song and Vienna Salvatori, but he was sent back each time.
Played by Alex MacQueen
This Master first appeared in the audio drama UNIT: Dominion, where he met the Seventh Doctor and pretended to be one of his future incarnations. He planned to control the dimensional energies of the universe through the use of two dimensional nodes, one of which he owned and the other of which was owned by the Doctor. This plan was failed and he later went on to meet the Eighth Doctor several times, working with others such as the Eminence and the Daleks. At one point he was body swapped with the decayed incarnation of the Master, who had been seeking to finally escape his husk of a body. In this body, he encountered the Fifth Doctor. The two Masters reunited later and teamed up against the Seventh Doctor, but their own inability to get on with one another led to their plan's downfall.
Played by Derek Jacobi
The Time Lords resurrected the Master to fight in the Time War, but the grand scale of it and the horrific events witnessed by the Master in it caused him to flee to the end of the universe in the year 100,000,000,000,000 on the planet Malcassairo, using a chameleon arch to turn himself into a human professor called Yana. Unaware of his true evil nature as the Master, Professor Yana tried helping humanity with the Utopia project alongside his assistant, Chantho, which would have allowed the human refugees there to board a rocket and leave to inhabit a new planet, Utopia. When the Tenth Doctor, Martha and Jack arrived, the sight of the TARDIS and the discussion of Time Lords and time travel caused Yana to vaguely remember his real self and the drums, eventually leading to him opening a fob watch he carried around with him at all times, which restored his Time Lord personality and memories as the Master. Deliberately sabotaging the Utopia project and killing Chantho, she used her final moments to retaliate and shoot him, forcing him to retreat into the Doctor's TARDIS and regenerate.
Played by John Simm
Regenerating into a much younger body, the newly regenerated Master locked the Doctor out of his TARDIS. Using his sonic screwdriver to lock the TARDIS between travelling only to 21st century Earth and Malcassairo, the Doctor, Martha and Jack followed the Master back to Earth using Jack's vortex manipulator. They soon found that the Master had become prime minister of Britain under the name of Harold Saxon. The Master killed the US president on live television and took over Earth as its new ruler, ageing the Doctor past his ability to regenerate and controlling the Earth for a full year. This plan was thwarted by Martha, who had roamed the Earth and spread the Doctor's name, encouraging people to say it so that the Master's Archangel Network would restore the Doctor to his usual self. Time reversed to moments after the death of the president and the Master was shot by his wife, Lucy. He refused to regenerate and died, but was later resurrected by a secret cult and got to work taking control of an immortality gate, which allowed him to transform every human on Earth into a clone of himself, naming them the Master Race. Freeing Rassilon and Gallifrey from the Time War, it descended upon the Earth. Rassilon revealed his plans to end time itself, but the Doctor successfully managed to reverse the Master's plan and sent them back into the Time War where they belonged, taking the Master with them. The Time Lords cured the Master of the drumming and sent him away from Gallifrey, where he ended up on a Mondasian colony ship and met his future incarnation, Missy, who killed him after he refused to stand by the Doctor's side in their battle against the Cybermen.
Played by Michelle Gomez
This incarnation of the Master was obsessed with reconciling her friendship with the Doctor, trying multiple times to make him believe the two of them weren't so different. She met the Twelfth Doctor after creating her own race of Cybermen from the dead, uploading their minds to the Nethersphere while converting their dead bodies to create an army. This was to provide the Doctor with an ultimatum, by either allowing her to use her new army to wage war across the universe or to stop her by accepting her offer to take control of the army for himself. However, unknown to her, Danny Pink hadn't fully turned into a Cyberman and so he took control of the Cyber army instead, leading them to their destruction. Missy was shot by one remaining Cyberman, the converted Brigadier, but she teleported away at the very last second to convince the Doctor and Clara that she died. Missy was later sent to a planet to be executed with the Doctor as her executioner, but he sabotaged the device so that it wouldn't actually kill her. He vowed to protect her body for a thousand years inside of a chamber called the Vault, which he kept under St. Luke's University in Bristol. During her imprisonment, Missy tried a different approach to reconciling her friendship with the Doctor, trying to turn over a new leaf and become good. Eventually believing she had made enough of a change, the Doctor took Missy to a Mondasian colony ship, where unknown to the two of them was her past incarnation in hiding. The two Masters met and her past self tried swaying her back over to the side of evil, though she ultimately chose to stand alongside the Doctor in their battle against the Cybermen, killing her past self to force him to regenerate. Outraged by her decision, her past self shot her with his laser screwdriver, claiming that he had apparently disabled her ability to regenerate. This was false, however.
Played by Gina McKee
Using an Elysian field, Missy regenerated inside of it to create an incarnation focused on the good sides of her nature. This resulted in an incarnation that named herself the Lumiat, appearing in Series 2 of Missy, who tried to follow in the Doctor's shoes of helping others and saving worlds. She couldn't help but interfere with her own past, stopping several of Missy's plans and trying to get her to become a better person. This eventually backfired on the Lumiat as Missy got bored of her and killed her, hoping whoever she regenerated into next would abandon this incarnation's good streak. Missy dumped the Lumiat's regenerating body onto a random planet and didn't stay around to witness it happen.
Played by Sacha Dhawan
While not made clear in the show where this incarnation of the Master comes in the timeline, he is generally considered by official sources to be post-Missy, and by default has to be at least after the Lumiat because of this. After hacking into the Matrix on Gallifrey, the Master discovered a hidden truth about the origin of the Time Lords, that they had really descended from a child from another universe who had been experimented on by a scientist named Tecteun in order to crack the secret to regeneration. The child was also the Doctor, later being turned back into a child after growing up. Angry at this, he destroyed Gallifrey and wiped out all of the Time Lords on it, leaving their bodies in the vaults. He led the Thirteenth Doctor to Gallifrey so that he could make her aware of her origins while converting the dead Time Lords on Gallifrey into brand new Cyber Masters, invulnerable Cybermen with the ability to regenerate from any damage. He left behind the death particle for the Doctor, a weapon capable of wiping out all organic life on a planet if used, wondering if she would actually use it or not and become just like him. The Doctor found that she couldn't do it, especially not on her home planet, but the responsibility was soon taken from her by Ko Sharmus, an ally she had made along the way who was partially responsible for everything that had happened. He took the death particle from her and activated it, killing himself in the hopes of taking the Master and his Cyber Masters with him.
Fatal Death Master
Played by Jonathan Pryce
This Master appears in the 1999 comedy sketch The Curse of Fatal Death as part of Red Nose Day. In this sketch, the Master meets the Ninth Doctor, played by Rowan Atkinson, on the planet Tersurus where he plans to announce his retirement and marriage to his companion Emma. The Master refuses to let this happen however and tries to kill the Doctor. This fails and he falls into the sewers of Tersurus. Hundreds of years pass from his point of view, and upon returning he reveals that he has teamed up with the Daleks yet again, falling into the sewers a second time afterwards and spending another few hundred years crawling through them. With the Daleks, the Master plans to control a zectronic laser beam that will give him control over the universe, but it becomes apparent that the Daleks are merely using him. It goes out of control and the Doctor regenerates through several different bodies trying to fix it, before finally regenerating into a final incarnation played by Joanna Lumley. Having saved the Daleks and her companion no longer loving her, the new Doctor and the Master leave together flirting with one another. Curiously, Missy references the events of this very adventure in the fifth series of The Diary of River Song, indicating that this comedy sketch actually happened. If this is the case, it is unknown where Jonathan Pryce's Master fits into the lineage of Master incarnations.
Played by Mark Gatiss
Stuck on Earth in the 1970s, this Master essentially performed the role the Third Doctor had in the main universe, helping protect Earth from various alien threats and invasions. His first appearance was in Sympathy for the Devil. He became desperate to escape and eventually did, fighting alongside the Doctor in the Great War that had caused their universe to begin dying. Wanting to escape into another universe, disintegrating people in a giant weapon disguised as a portal to give him enough energy to escape just by himself. This plan was stopped by the Doctor and Bernice Summerfield, with the Master thrown into the portal himself by the very people he had been luring into it. He survived and planned to take the Doctor's position as president of the universe, something the Doctor was all too happy to let him have as he was sick of the position.</b>
I do find it interesting that the Doctor had two Time Lord enemies before the Master was introduced, those being the Monk / Time Meddler and the War Chief. It's a little sad that they never brought back the Monk after his second appearance, he was great.
I had forgotten about the War Chief. But the Monk was very memorable. I believe that there was an early Big Finish program that featured him, but I might be considering him with the Toymaker.
I haven't kept up with the newer BF. I have way too many audiobooks to listen to. I did a massive Doctor Who listen about 5 years ago, but it has been pretty sporadic since then. I will have to catch up sometime soon