At some point, the Master regenerated into a female incarnation. As such, she adapted her name of “the Master” into “Missy“, short for “Mistress”.
She managed to escape from the pocket universe in which Gallifrey existed. She also managed to acquire a vortex manipulator, which she used for time travel.
Working with the Cybermen, Missy founded the 3W Institute, in order to create a Cyberman army of the dead. She uploaded dying minds to the Nethersphere; a virtual reality housed within a matrix data slice. This reality changed and rewrote the minds, removing their emotions before re-downloading them into their Cyber-converted bodies. (TV: Dark Water)
Missy decided to maneuver Clara Oswald into becoming the Doctor’s companion, believing that Clara was just the right companion to attract the Doctor’s interest and make it easier for Missy to emotionally manipulate him, (TV: Death in Heaven) showing him “the friend inside the enemy [and] the enemy inside the friend.” (TV: The Witch’s Familiar) Ashildr believed that Missy placed the two together so that that the Doctor and Clara in tandem would become the Hybrid of Gallifreyan myth. (TV: Hell Bent)
At some point before 2013, Missy gave Clara the Doctor’s phone number, claiming that it was a tech support line, leading to Clara to meet the Eleventh Doctor. (TV: The Bells of Saint John, Death in Heaven) She then kept the Doctor and Clara together into the Doctor’s twelfth incarnation by placing an ad in a newspaper for Mancini’s Family Restaurant. (TV: Deep Breath, Death in Heaven)
Missy went along the Doctor’s timeline and greeted people who died in connection with him, (TV: Death in Heaven) such as the Half-Face Man (TV: Deep Breath) and Gretchen Carlisle. (TV: Into the Dalek) Finding this made her “a bit busy”, (TV: The Caretaker) Missy began to secretly monitor the Twelfth Doctor and Clara, (TV: Flatline) as she did when Earth was saved from a solar flare by a forest that grew overnight. (TV: In the Forest of the Night)
Missy finally met the Twelfth Doctor and Clara at one of 3W’s mausoleums, which was hidden inside St Paul’s Cathedral (TV: Dark Water) with dimensional engineering. (TV: Death in Heaven) Initially posing as an android and sharing a kiss with a very confused Doctor, she revealed her true identity to him as the Cybermen marched out onto the streets of London. (TV: Dark Water)
Missy was quickly captured by UNIT, having anonymously tipped them off on the Cybermen’s presence. She watched as Cybermen flew into the sky exploded above major population centers, creating clouds that rained Cyber-pollen, turning the dead into Cybermen. Taken onto Boat One along with the Doctor, she sent out a signal to the Cybermen, to attack the plane before freeing herself and disintegrating Osgood. Missy then ordered the Cybermen to remove a piece of the fuselage, causing Kate Stewart and the Doctor to be sucked out before ordering the Cybermen to destroy the plane, and teleporting away. In the Nethersphere, Missy and Seb watched the Doctor free falling and saving himself by using his key to summon the TARDIS. When Seb got overexcited at this dramatic turn of events, Missy casually disintegrated him. The Doctor found out from the Cyber-converted Danny Pink that she planned to have the Cyber-pollen fall again, killing humanity, who would be reborn as Cybermen. She teleported into the graveyard to which the Doctor had piloted his TARDIS. Missy then unexpectedly gave the Doctor control of the Cybermen, wanting him to use them as his army, in the hopes of proving the similarities between the two Time Lords. However, after pondering the idea, the Doctor proclaimed himself to be simply an “idiot” with a box rather than a general or any sort of leader. He turned control over to the Cyber-converted Danny, who ordered the army into the sky to destroy themselves, dispersing the threatening rain clouds.
After the threat of the Cybermen had ended, Missy gave the Doctor coordinates to the current location of Gallifrey, lying to the Doctor that the planet had returned to its original location, and that she and the Doctor could travel there together. However, Clara, using Missy’s own weapon, decided to kill her. The Doctor wouldn’t let Clara kill Missy, decided to kill his old friend himself — not out of vengeance, he told her, but to save Clara’s soul. Before he could fire the weapon, Missy was shot by a rogue Cyberman, who was revealed to be the Doctor’s old friend, Brigadier Lethbridge-Stewart, (TV: Death in Heaven) but used the blast from the blaster to recharge her vortex manipulator and escape undetected. (TV: The Witch’s Familiar)
Some time later, after he was summoned by Davros, (TV: The Magician’s Apprentice) the Twelfth Doctor left his confession dial with Ohila (WC: Prologue) for her to deliver to Missy. Missy got the attention of both Clara and UNIT by freezing all the airborne planes on Earth in time. Summoning Clara, she showed her the Doctor’s confession dial, the Time Lord equivalent of a will. Together, she and Clara tracked the Doctor down to Essex in 1138.
Unbeknownst to them, they led Colony Sarff right to the Doctor. Sarff then took the three to Skaro, although they were led to believe that they were still in deep space. While the Doctor was taken to Davros, Missy and Clara escaped their cell, but were soon captured by a Dalek. They were taken to the other Daleks before they were both seemingly exterminated. (TV: The Magician’s Apprentice) However, Missy and Clara had survived by using the Dalek blasts to recharge her vortex manipulator and teleporting from the Dalek city.
Missy and Clara entered the Dalek sewers, composed of rotting Daleks, using Clara to lure a Dalek there. She cut through its case using a brooch given to her by the Doctor made of dwarf star alloy, enabling the rotting Daleks to kill it. She put Clara inside the case and pretended to be her prisoner, enabling her to re-enter the Dalek control room. When the Daleks began to gain Time Lord regeneration energy, Missy used their incapacitation to find the Doctor. She used a Dalek gun to shoot Colony Sarff, saving the Doctor. She then watched as the Doctor toyed with Davros about the revived Daleks in the sewers and even tapped Davros’ Dalek eye as they made their escape.
When the city was being destroyed by the regenerated sewer Daleks, Missy tried to trick the Doctor into killing Clara inside the Dalek. However, the Doctor realized the deception and told Missy to run. She was surrounded by Daleks when the city crumbled in on itself, but purported that she had “a really clever idea”. (TV: The Witch’s Familiar)
After she was captured by an unnamed species on an unnamed planet, Missy was sentenced to death. In accordance with their Fatality Index, the Twelfth Doctor was chosen to carry out the sentence. However, he sabotaged the execution machine so that she was knocked unconscious instead of being killed. Swearing an oath to guard Missy’s “body” for a thousand years, the Doctor scared the executioners away and had Nardole place her inside a Quantum Fold Chamber. (TV: Extremis) The Doctor and Nardole transported the vault to St Luke’s University, where they continued to guard it for several decades. (TV: The Pilot)
In 2017, (TV: Knock Knock) after the Doctor began traveling with Bill Potts, (TV: The Pilot) Missy began banging on the doors of the vault, only for Nardole to assert that he would stand guard and prevent her escape. (TV: Thin Ice) When he later double-checked the locks, she started playing Für Elise on a piano the Doctor had given her. Once Nardole was dismissed by the Doctor, Missy started playing Pop Goes The Weasel when the Doctor told her about his adventure at 11 Cardinal Road. (TV: Knock Knock)
After he received an email from a simulation of himself warning of an upcoming invasion, the Doctor became tempted to release Missy from the vault. (TV: Extremis) When the Monks later occupied the Earth, the Doctor was kept prisoner for six months. After Bill helped him escape, he decided to consult Missy on how to defeat the Monks. Missy revealed she had dealt with them before, and that the only way to weaken their grip on power was to kill the psychic lynchpin being beamed to the whole planet. After the Monks had been driven off-world, the Doctor visited Missy in the vault again. This time, she claimed to be in deep regret of all the people she had killed throughout her lifetimes. The Doctor assured her she was making good progress on her redemption. (TV: The Lie of the Land)
Nardole later released Missy from the vault so that she could help him return the TARDIS to 1881 Mars. However, the Doctor reminded her she was acting against their agreement and that he would put her back in the vault. (TV: Empress of Mars)
Deciding Missy may be worth trusting, the Doctor released her from the Vault to perform maintenance work on the TARDIS while he took Bill and Nardole to find the lost Roman legion. Missy finished the work, then took to watching the Doctor at work until he returned some days later. Nardole was frustrated the Doctor had freed her, but he brushed him off, preferring to see if Missy had learned anything. Missy later cried as the Doctor watched on, both wondering if it was possible for them to be friends again and whether Missy was finally becoming the person the Doctor had desired to make them. (TV: The Eaters of Light)
To test Missy’s goodness, the Doctor recruited Bill and Nardole to be her “companions” and followed a distress signal to a colony ship while the Doctor monitored Missy’s progress from the TARDIS. Missy introduced herself to the cameras as “Doctor Who”, telling Bill that it was the Doctor’s original name; she addressed Bill as “Exposition” and Nardole as “Comic Relief”. However, she was ill-prepared to handle a frightened and violent crew member, Jorj, who subsequently shot Bill; she was carried off by passengers from the lower decks. Missy accompanied the Doctor and Nardole down the elevators to Bill’s floor, where the Doctor left her in charge of gleaning information from the computers. She discovered that the colony ship originated from Mondas while being pestered by a man called “Razor”, who, upon confrontation, revealed himself to be her past self. (TV: World Enough and Time)
Together, the Master and Missy beat on the Doctor, taunting him about his various deaths and regenerations. The two versions of the Master take the Doctor to the roof of the hospital where they revel in “the genesis of the Cybermen.” However, the Doctor simply calls it “parallel evolution” that has happened in many places and reveals that he has reprogrammed the Cybermen to see Time Lords as humans, causing the Cybermen to attack them. The Master and Missy attempt to hold them off, but the Doctor states that there is only one way out: him, so Missy knocks the Master unconscious with her sonic umbrella. Missy claims to have always been on the Doctor’s side, but seems unsure if she really was or not, admitting that she was of two minds “but fortunately the other one is unconscious.” The Doctor contacts Nardole who rescues them in a shuttlecraft, but the Doctor is attacked by a Cyberman. Missy and the Master attempt to abandon him, but are stopped by Bill who has retained her humanity. The five then use the shuttlecraft to reach Floor 507.
On Floor 507, Missy locates the lifts and explains to her past self that she has no memory of the event as their timelines are out of synch when they are together, meaning the Master and thus Missy could retain no memory of it. Missy shows genuine empathy for Bill’s situation, disgusting the Master with what she has become. Unthinking, Missy summons the lift which brings an evolved Cyberman to Floor 507. Together, the Doctor, the two Masters and Bill destroy it, but realize that the evolved Cybermen will now be on their way to convert everyone. While Missy suggests going to the bridge to get the Doctor’s TARDIS, the Doctor states that its impossible as the time dilation will mean that the Cybermen will have evolved far too much if they go higher than five floors above.
As the Doctor and Nardole attempt to come up with a plan, Missy suggests that she and the Master flee in his TARDIS, located on the bottom floor. The Master admits that he burned out the dematerialization circuit trying to get away from the black hole, causing Missy to shove him up against the wall and reveal that she has remembered something from her time on the ship as the Master: pushing her past self up against a wall and making him promise to always carry a spare circuit on him which she removes from her pocket. Before the Masters depart, the Doctor attempts to convince them to stand with him and help the people. While the Master is unmoved, Missy appears to be. However, while she states she would like nothing more than to stand with him, she won’t.
The Master and Missy make their way to the lift where they dance briefly. Stating that she remembers what it’s like to be this Master and how much she had loved being him, Missy stabs her past self in the side with a small hidden knife, mortally wounding him. The Master expresses his admiration for Missy’s actions and Missy helps the Master to the lift. Missy explains that she made the wound precise so that the Master will have time to reach his TARDIS before regenerating into Missy. Missy has realized that the Doctor is right: it is time to stand with him. As Missy departs, the Master screams that he will never stand with the Doctor and shoots her in the back with his laser screwdriver, mortally wounding her beyond regeneration. The two laugh and the Master tells Missy that their perfect ending is that “we shoot ourselves in the back.” As the Master departs for his TARDIS, Missy collapses to the ground and dies of her wounds. (TV: The Doctor Falls)
Following his failed resurrection, the Master regenerated into a woman. (TV: Dark Water) Though he had previously preferred a male form, (PROSE: The Novel of the Film) the Master fully embraced her new gender, changing her title to “Mistress”, shortening it to “Missy”, and, considering herself to be “old fashioned”, insisted on being addressed as Time Lady, (TV: Dark Water, The Witch’s Familiar) while nicknaming herself the “Queen of Evil”. (TV: Death in Heaven) She also adopted a Scottish accent, claiming she would keep it after taking a liking to the Twelfth Doctor’s accent, (TV: Deep Breath) occasionally utilizing other accents when she felt the need. (TV: Death in Heaven, The Witch’s Familiar)
No longer choosing to hide behind a rational persona, Missy openly described herself as “bananas”, but took offence when Danny Pink called her a “lunatic”. (TV: Death in Heaven) She adopted a bubblier personality, (TV: Deep Breath, Death in Heaven) and took on more choreographic movements. (TV: Deep Breath, Dark Water, Death in Heaven, The Witch’s Familiar) She also displayed tendencies of being a show-off, such as when vastly enlarging her face on a UNIT monitor in a comical manner to show UNIT than she could. (TV: The Magician’s Apprentice)
Even though she employed a welcoming and sociable façade, (TV: Deep Breath, Into the Dalek, Dark Water, Death in Heaven) Missy exhibited loneliness and a desire for the Doctor to identify with her when she professed her entire plan to be an action to rekindle their childhood friendship. She also manifested fear, belying her facade of nonchalance when she thought he would kill her to spare Clara’s soul, (TV: Death in Heaven) and also showed momentary terror of being on Skaro. (TV: The Magician’s Apprentice)
Believing that the Doctors saving of Gallifrey was meant to save only her, (TV: Death in Heaven) Missy became enamored with the Doctor, telling the Half-Face Man that, while the Doctor could be mean to others, he would not be with her because he “loved [her] so much”. She openly referred to him as her “boyfriend”, (TV: Deep Breath) tracked his movements across time and space, (TV: Flatline, In the Forest of the Night, Death in Heaven) and mockingly professed that her hearts “belonged to [the Doctor]” after passionately kissing him. (TV: Dark Water) She also began planning Osgood’s murder after the Doctor invited Osgood to travel with him, (TV: Death in Heaven) and toyed with the notion of shooting the Doctor in jealousy when he went to save Clara. (TV: Dark Water) Unlike the “Saxon” Master, Missy was open to the idea of being the Doctor’s prisoner, so long as she and him were together. (TV: Death in Heaven) Despite previous implications that their relationship was romantic, Missy adamantly denied that she loved the Doctor, even showing disgust at the thought, insisting it to be a complicated friendship. She seemingly preferred to remain the Doctor’s nemesis, expressing irritation when the Doctor called Davros his arch-enemy. (TV: The Magician’s Apprentice)
Instead of a hunger for domination, Missy “need[ed] [her] friend back”, creating an army of Cybermen from Earth’s dead to give to the Doctor as a birthday present. However, this was revealed to be a plot to convince the Doctor that they were not so different by giving him an army with which to “right wrongs”, her plan being to give him an unstoppable force to corrupt his mind, turn him to her way of thinking, and ultimately rebuild their friendship. (TV: Death in Heaven) She later employed the Doctor’s hatred of the Daleks to get him to kill Clara when she had been placed in a Dalek casing. (TV: The Witch’s Familiar) Despite her desire to reconnect with him, Missy enjoyed taunting the Doctor about the status of the lost Gallifrey, and how she didn’t have to divulge the planet’s location to him. She also had no qualms about him falling to his death after destroying Boat One, though considered it a boring demise that lacked finesse. (TV: Death in Heaven) She also enjoyed having information that others did not, such as having knowledge of the Doctor’s past that others could not argue with. (TV: The Magician’s Apprentice)
Missy retained her predecessors’ sadistic tendencies, demonstrating cruel pleasure at taunting her victims before she killed them, such as telling Dr Chang she would miss him and promising to always keep a picture of him “looking so sweet” before she murdered him. (TV: Dark Water) She also encouraged Osgood to have more self-confidence, while counting down to her death to torment her. However, she atomized Seb without a second glance for no reason other than that the AI was annoying her. (TV: Death in Heaven)
Viewing everything as being born to die, Missy held no regrets when it came to murder, describing her urge to kill as akin to a child wanting to pop a balloon, (TV: Death in Heaven) and having a preference for killing “clever-clogs” because they “[made] the best faces”. (TV: The Witch’s Familiar) Missy also held no respect for the dead, using dead human bodies to create a Cyberman army, (TV: Dark Water) as well as crushing Osgood’s glasses under her heel while posthumously thanking her for being “yummy”. (TV: Death in Heaven)
Missy was a devious planner, with the Doctor surmising that she had exploited the paranoia the super rich had towards their mortality to use their wealth and mortal remains for the 3W Institute and create a new race of Cyberman. (TV: Death in Heaven) While trapped on Skaro with Clara Oswald, Missy demonstrated fluid planning as her desires changed from wanting to ally with the Daleks, (TV: The Magician’s Apprentice) to wanting to help the Doctor, to then wanting the Doctor to unintentionally kill Clara. (TV: The Witch’s Familiar)
Missy was a skilled manipulator, able to maneuver others into place with ease by exploiting their desires, such as Osgood’s desire for the Doctor’s approval, the Doctor’s desire to find Gallifrey, (TV: Death in Heaven) and Clara’s desire to save the Doctor from the Dalek City. (TV: The Witch’s Familiar) She was also a convincing liar, especially when using her talent for manipulative reasons. She pretended to be a welcome droid, and even improvised a mnemonic acronym to go with her name, when she first encountered the Twelfth Doctor, (TV: Dark Water) and tricked him by giving him false coordinates to where Gallifrey had supposedly reappeared after her Cyberman army had been destroyed. (TV: Death in Heaven)
While she was as cunning as her predecessors, Missy’s impractically long plan for her Cyberman army was not without its faults; giving the dead a choice about whether to be cyber-converted or to live in the Nethersphere, (TV: Dark Water) trying the blow up the Doctor on Boat One despite him being instrumental in her master plan, and basing her entire plan on a moral decision that she had seen the Doctor make numerous times in previous incarnations; that of allowing one evil act to ensure the greater good, and expecting a different outcome. Missy also opted for one solitary scheme with virtually no contingencies or back-up plans in place to help steer events back towards her favor like her previous incarnations employed, instead opting to give the Doctor false hope of reaching Gallifrey after she was beaten, (TV: Death in Heaven) and walking away with nothing but taunts to say when the Doctor didn’t kill Clara. (TV: The Witch’s Familiar)
While building up to a murder, Missy would insisted that her victim “say something nice” to her, and would wait patiently for them to reply. (TV: Dark Water, Death in Heaven, The Magician’s Apprentice) She also insisted that anyone aiming to kill her do the same with her, (TV: Death in Heaven) and would take offence if a threat to kill her was not carried out. (TV: The Witch’s Familiar) She also puckered her lips and blew kisses before killing each of her victims, even applying lipstick before killing Osgood and her guards. (TV: Dark Water, Death in Heaven)
Missy could be needlessly cruel in her interactions with others, such as taunting Clara Oswald about her dead boyfriend, (TV: The Magician’s Apprentice) and pushing Clara down a hole to test its depth. (TV: The Witch’s Familiar) She also ordered the death of Belgians for no reason, (TV: Death in Heaven) vaporized UNIT personnel to prove she had “not gone good,” (TV: The Magician’s Apprentice) and was believed to have united Clara and the Doctor together just to see what chaos would result from their clashing personalities. (TV: Hell Bent)
Missy showed a liking for singing, substituting her name in with “Hey Mickey” while in UNIT custody, and singing a verse from “Happy Birthday, Mr President” when giving the Doctor control of a Cyberman army. (TV: Death in Heaven) She pulled a similar stunt involving “Hey Mickey” lyrics via text communication when she announced her presence to UNIT by halting all airplane traffic, and, when imprisoned by Colony Sarff, she passed the time by partaking in opera singing. (TV: The Magician’s Apprentice)
Sharing the Doctor’s observational skills, Missy could tell a man she had killed was a married father by the ring on his finger and the detection of “baby leakage” on his jacket. (TV: The Magician’s Apprentice)
At a later point in her life, Missy appeared to change or at least be trying to. At her execution, while initially bringing up what she heard about the Doctor and River Song on Darillium, Missy didn’t take the opportunity to taunt the Doctor over River’s death and instead offered her sincere condolences for his loss. (TV: Exremis) After helping the Doctor defeat the Monks, Missy expressed a deep regret for her actions and a desire for redemption. (TV: The Lie of the Land)
After being confronted with her past self, Missy appeared to be torn between who she was and who she wanted to be. While with the Master, Missy took up some of her old behaviors such as taunting the Doctor, but claimed that she was faking it and was always on his side. However, she honestly admitted that she wasn’t sure if she was telling the truth and had been of two minds over it. Unlike the Master, Missy was visibly moved by the Doctor’s speech and request for their help, tearfully admitting that she would like nothing more to help him, before stating that she wouldn’t. Secretly, Missy had realized that the Doctor was right, that it was time to stand with him and believed that her life had always been leading to her standing with the Doctor instead of against him. To this end, she forced the Master to regenerate into herself to ensure this would come to pass. (TV: The Doctor Falls)
Missy looked like a mature woman with pronounced cheek bones, and light blue eyes. Her black hair was wild and free, but held in place in an up-do. She also adopted a Scottish accent like the Twelfth Doctor.
Fashioning herself in Victorian-styled garb, Missy wore a starched collared blouse (TV: Deep Breath) with cameo brooch made of Dark star alloy under her throat, (TV: The Witch’s Familiar) along with a high waisted skirt that cut to ankle length, and a croak lengthen jacket which puffed up at the shoulders and dark lapels. She also wore black ankle boots with a sharp toe and tapered heels. Completing the ensemble was a black boater hat worn at a rakish angle, with an arrangement of black and red berries on the brim and a black veil over the top.
For further accessories, Missy wore a spiked bracelet on her left wrist, carried around a black umbrella, and wore a ring on her left hand. (TV: Deep Breath)
Missy varied the colors of her clothes, with the design coming in black, (TV: Deep Breath) bottle green, (TV: Into the Dalek) a shade of dark orange, (TV: The Caretaker) plum, (TV: Flatline) and violet. (TV: The Magician’s Apprentice)
Imprisoned in the Vault, Missy was unable to have her hair cut, leading to it growing and looking messier than before. (TV: The Lie of the Land)