Thirteenth Doctor

The Thirteenth Doctor was the first female incarnation of the Time Lord known as the Doctor and the second incarnation of the Doctor's second regeneration cycle granted by the Time Lords during the Siege of Trenzalore.

After being separated from her TARDIS during her post-regenerative trauma, the Doctor was assisted in her recovery by Graham and Grace O'Brien, Ryan Sinclair, and Yasmin Khan. Following a battle with the Stenza Tim Shaw, that resulted in Grace's death, the Doctor inadvertently brought Graham, Ryan and Yasmin with her in her search for her TARDIS.

After finding the TARDIS, the Doctor started her mission to take Graham, Ryan and Yaz back home, making several accidental trips along the way. After briefly returning to Sheffield, Graham, Ryan, and Yaz officially joined the Doctor in her travels.

A day to come
When encountering the "Vortex Butterfly", the Tenth Doctor was cryptically told that he would not be "limited" to "thirteen lives". (COMIC: Vortex Butterflies)

When the Twelfth Doctor broke his toe, Clara Oswald suggested that he regenerate to heal the injury, but he berated the idea as a waste. (PROSE: The Blood Cell)

When threatened by Captain Lundvik, the Twelfth Doctor told her she would have to shoot him, Clara Oswald and Courtney Woods, but warned that she would "have to spend a lot of time shooting [him] because [he would] keep on regenerating." Clara, during a falling out with the Doctor, later threatened to "smack [him] so hard [he would] regenerate". (TV: Kill the Moon)

While suffering from the common cold, the Twelfth Doctor, overreacting to the illness, considered the possibility of needing to regenerate. (COMIC: The Day at the Doctors)

When the Twelfth Doctor confronted Rassilon in Gallifrey's Drylands after escaping from his confession dial, Rassilon contemplated using his gauntlet to force the Doctor to regenerate as a method of torture, rhetorically wondering how many regenerations the Doctor had been granted, but was interrupted before he could attack the Doctor with the gauntlet. (TV: Hell Bent)

After the Monk invasion, the Twelfth Doctor needed to know if his companion, Bill Potts, was under the control of the Monks, and deceived her into shooting him in a rage to see if she had succumbed to the mind control, secretly putting blanks in all the guns, and faking his regeneration to complete the illusion. He made it look like the process had started, but emerged as himself to show her that he had deceived her. (TV: The Lie of the Land)

After the Twelfth Doctor was captured by and  on a Mondasian colony ship, they debated throwing him off a hospital roof to kill him, but decided against it when they realised their uncertainty on how many regenerations he had remaining, believing they "could have been up and down the stairs all night." (TV: The Doctor Falls)

Post-regeneration
After the Twelfth Doctor was gravely wounded by the Cybermen on the Mondasian colony ship, the regenerative process began. However, tired of "being someone else", the Doctor delayed the change for several weeks, (TV: The Doctor Falls) until an encounter with his first incarnation, Archibald Hamish Lethbridge-Stewart, and the Testimony caused the Doctor to concede that another regeneration wouldn't "kill anyone". After taking a final look at the universe and providing advice to his next incarnation, the Doctor regenerated inside his TARDIS in an explosive fashion. (TV: Twice Upon a Time)

As they regenerated, the Doctor relived memories from each of their past lives while the Twelfth Doctor's personality continued to give advice. They remembered the magnificence of their TARDIS; (COMIC: The Many Lives of Doctor Who) their first human friends, Ian and Barbara, and a time the First Doctor visited a Pathicol spiritual site with Ian, Barbara, and Susan; (COMIC: The Path of Skulls) the strangeness of some of their adventures, including one the Second Doctor had with Jamie, Ben, and Polly involving living playing cards; (COMIC: Card Conundrum) their love for London, and how the Third Doctor and Sarah Jane saved the city from the Dahensa; (COMIC: Invasion of the Scorpion Men) and their love for parts of Earth outside the UK, such as New York City, where the Fourth Doctor and Romana II retrieved a psychic sales voucher for two Ra'ra'vis. (COMIC: Time Lady of Means)

As she continued the recollections, the Doctor settled into a new body. She next remembered (COMIC: The Many Lives of Doctor Who) Gallifrey and the regeneration limit, and how the Fifth Doctor journeyed into the Cloisters with Nyssa, Tegan, and Turlough and worked with Ophiuchus to break the limit; (COMIC: Ophiuchus) how the Sixth Doctor and Peri saved the Triumvirs from the Haxeen; (COMIC: Virtually Indestructible) the Master, and how the Seventh Doctor and Ace once stopped from murdering Julius Caesar; (COMIC: Crossing the Rubicon) how things weren't always as they appeared, as evidenced during the Eighth Doctor and Josie's rescue of an Omsonii; (COMIC: The Time Ball) and the Last Great Time War, in particular when the War Doctor and Dorium Maldovar destroyed the weapons factories of Villengard. (COMIC: The Whole Thing's Bananas)

As the regeneration finished, the Doctor noticed that her clothes no longer fitted and felt "there was something different about this body". (PROSE: Twice Upon a Time) After the Twelfth Doctor's ring fell off her finger, (TV: Twice Upon a Time) the Doctor remembered how the Ninth Doctor had to relearn to be "the Doctor", and once, with Rose and Jack, saved a Volsci; (COMIC: Return of the Volsci) how the Tenth Doctor, Gabby, and Cindy helped Elizabeth Garrett Anderson become the first female doctor in England; (COMIC: Nurse Who?) her wife River Song and the time the Eleventh Doctor and Alice saved River from Shoalies; (COMIC: Without A Paddle) and, finally, the Daleks, and the Twelfth Doctor and Bill's encounter with a Kaled harvester ship. (COMIC: Harvest of the Daleks)

With the new incarnation becoming a certainty instead of a possibility, her actualised potential sent postcards with pictures of herself in baggy black clothing to various friends, including V. M. McCrimmon and Grandfather Halfling in the City of the Saved, as a sort of "hello to the world". McCrimmon had letters from two other potential versions of the new incarnation, which were made narratively unstable and destroyed by the postcard. (PROSE: Postscript)

Still hearing her predecessor in her head, (COMIC: The Many Lives of Doctor Who) the Doctor staggered to the console in a daze. Examining her face in a reflection, the Doctor saw that she had regenerated into a woman, and felt that the change was "brilliant". After she pressed a button on the console, the TARDIS suddenly spiralled into chaos, caused in part by the explosive regeneration. Subsequently, she was thrown out through the TARDIS doors in the confusion after the time rotor exploded, with the TARDIS itself vanishing without the Doctor as she fell towards Earth. (TV: Twice Upon a Time)

Crashing through the ceiling of a train that was being sieged by an alien energy coil, the Doctor took charge of the situation and met Yasmin Khan, Ryan Sinclair, Graham and Grace O'Brien. Still uneasy after her change, the Doctor soon pulled herself together long enough to defeat Tim Shaw, a Stenza who was controlling the coil and had gone hunting for a human to take back to his planet as a trophy. Unfortunately, although she was able to force Tzim-Sha to abandon his hunt by tricking him into downloading the DNA bombs he had tried to plant in her and her new friends into himself, Grace was killed when she was thrown off a crane while trying to overload the energy coil. Out of respect, the Doctor went to Grace's funeral, where she comforted Ryan. (TV: The Woman Who Fell to Earth)

Due to falling out of the TARDIS, (TV: Twice Upon a Time) the Doctor lost everything in her pockets including her sonic screwdriver, forcing her to make a new one using a crystal from Tzim-Sha's transport pod and scrap metal. After the funeral, she went to a charity store and chose a new outfit. Rigging up Tzim-Sha's transport pod, the Doctor transported herself to where she traced the TARDIS, accidentally bringing Graham, Yaz and Ryan with her. (TV: The Woman Who Fell to Earth)

Winding up on a spaceship crash landing on the planet known only as Desolation, the Doctor and her companions accompanied a duo of space racers, Epzo and Angstrom, in search of the "Ghost Monument", her TARDIS. (TV: The Ghost Monument) While on Desolation, the Doctor overlooked the ocean as she considered her uncertainty about her future, knowing only that it would be "amazing".(COMIC: The Many Lives of Doctor Who) Managing to survive the deserts and SniperBots hidden throughout the ruins, the Doctor uncovered a sabotaged science experiment conducted by another alien race subjugated by the Stenza, who had forced them to create weapons that would eventually posion the planet and reduce it to a barren wasteland. Cornered by their Remnants, who attempted to read her mind, the Doctor destroyed them by igniting the gas in the air. Ensuring the space racers got off the planet, the TARDIS returned to the Doctor and she was elated by the redecorating of her beloved ship, before taking off to return the others home. (TV: The Ghost Monument) However, the Doctor had some trouble piloting the TARDIS with the new controls. (TV: Rosa)

Returning to Sheffield
The Doctor tried to pilot the TARDIS back to Sheffield, but made several accidental stops along the way. (TV: Rosa) Some of these included a singing waterfall made of pink crystals, a unicorn sanctuary on a lost moon and the Big Bang. (PROSE: The Good Doctor)

After fourteen attempts to return to Sheffield, the Doctor accidentally took them to Montgomery, 30 November 1955. Wandering round searching for the source of the artron energy that forced them there, they encountered a racist serial killer from the 79th century named Krasko had used a vortex manipulator to travel into the past to prevent Rosa Parks from initiating the Montgomery Bus Boycott in the hope doing so would prevent equality between races. However, the Doctor destroyed Krasko's manipulator and Ryan used the displacement gun to send Krasko far into the past, where he couldn't hurt anyone else. The Doctor then helped undo all of Krasko's meddling, ensuring Rosa went on to do as history intended. (TV: Rosa)

The Doctor eventually got the trio back to Sheffield, but decided to stick around to have at least one last meal at Yaz's flat. She met Yaz's parents and sister, but soon became distracted by the threat of giant spiders, mutated due to the carelessness of Jack Robertson, an entrepreneur with presidential ambitions, whose companies had improperly disposed of various waste products under the hotel, including lab samples that had been working on enlarging spiders, unaware that some of the disposed spiders were still alive and mutated their fellows. The Doctor, Graham, Ryan and Yaz, working with Robertson, Yaz's mother Najia Khan, and Doctor Jade McIntyre (one of the scientists working on the spiders), were able to trap most of the spiders in Robertson's panic room. Robertson killed the spider mother, much to her outrage.

Later that night, as the Doctor prepared to depart, the three returned to the TARDIS, explaining that they had all chosen to stay; Graham decided that he would cope better with the grief of Grace's death by seeing more of the universe in the TARDIS rather than staying in the house with so many memories of her, Ryan couldn't take staying in the warehouse where he worked when travel in the TARDIS was available as an alternative, and Yaz felt that she wanted more of the universe than being driven insane by her family. The Doctor asked them to consider this, as once she pulled the lever she was never sure where the ship would go and couldn't guarantee their safety, but they all accepted this risk, pulling the dematerialisation lever together to continue their journeys. (TV: Arachnids in the UK)

Team TARDIS
The Doctor and her companions travelled to the planet Gatan, arriving in the City of Radiant Stone in the midst of war. As the group split in twos to help a lost girl called Tondi find her mother, the Doctor and Yaz were attacked by a looter called Gorny, after the former asked him for directions. The Doctor was able to subdue the looter, but before he could divulge to the Doctor why the city was in such a state, they both got caught in the crossfire between two enemy warriors, one calling himself a member of the Kith-kind. (COMIC: The Warmonger)

After halting a war on the planet Lobos between the loba and human colonists, the Doctor and her companions departed in the TARDIS. When they attempted to return - to retrieve Ryan’s mobile phone - the TARDIS slipped almost six hundred years into the future, where the planet was now ruled by human zealots, served by slave loba, whose religion was largely based on a misinterpreted throwaway joke by Graham, who was worshipped by them as "The Good Doctor". First relegated to the background and having to do things through Graham's god-like authority, the Doctor inevitably came into conflict with the ruling Temple of Tordos. She had to fight an artificially enhanced loba Tromos to the death. In the end, the Doctor succeeded in uncovering the lie of the zealots, setting the record straight and brokering a lasting peace between humans and loba. (PROSE: The Good Doctor)

Undated events

 * The Doctor once posed as a museum curator in Venice. visited her to ask for the location of items that had been stolen from her in the 14th century. Missy took an old map from her and left. Later, the Doctor saved Antonia from being left behind in 14th century Venice, returning her to the present. She left Antonia with a note chastising Missy for her actions and that she would have to try harder next time. She then cleared out her office and told her assistant to tell anyone who asked that "the Doctor doesn't work here anymore." (PROSE: The Liar, the Glitch and the War Zone)
 * At some point, the Doctor met Cass and gave her a bandolier. (PROSE: The Day of the Doctor)
 * The Doctor had an encounter with Alistair Gordon Lethbridge-Stewart that was recorded on video. (PROSE: Avatars of the Intelligence)
 * At some point before 5 March 2005, the Doctor was photographed "running away from a giant frog in front of Buckingham Palace". (PROSE: Rose)
 * While sitting on a bench in Henry VIII's third-favourite garden, the Doctor thought about the lesson the Moment had wanted to impart. The Moment then joined her on the bench, and when the Doctor asked her why she had helped him the day he saved Gallifrey, she said it was because she did not want to be used. About a year later, when the Doctor stood in a fountain at the heart of the Villengard banana groves, the Moment appeared again, continuing their conversation. The Moment told her that she helped because the universe had a need for the Doctor, and at that point, they were in danger of stopping. Pleased that she finally had an answer, the Doctor went back to the TARDIS with a renewed vigour. (PROSE: The Day of the Doctor)
 * The Doctor once offered to babysit a young Judoon refugee from a "big fight" on a world far from Earth, but was prevented from doing so by other Judoon. She went to 1966 Dublin after the young Judoon landed there, but found it was already in the care of Patricia. After the Judoon returned to its people, the Doctor gave few encouraging words to Patricia. (PROSE: The Rhino of Twenty-Three Strand Street)

Personality
Being the one who "sort[ed] out fair play throughout the universe", the Thirteenth Doctor was a warm and passionate individual, willing to take great risks to protect an innocent life, and would even apologise if she exposed someone to a grotesque sight that disturbed them. She was proud that she would never refuse anyone help if they needed it. (TV: The Woman Who Fell to Earth)

She implored those around her to ask questions about a situation, and showed no irritation on how off topic the questions got, (TV: The Woman Who Fell to Earth) even showing excitement when the right questions were asked, (TV: Rosa) but would clarify when "the wrong question" to a situation was being asked. (TV: Arachnids in the UK)

The Thirteenth Doctor would run into a situation without a strategy in mind, hoping to come up with a plan in the heat of the moment. (TV: The Woman Who Fell to Earth)

The Thirteenth Doctor was not above being secretive and cryptic, handing an annotated map of 14th century Venice, without explaining it and leaving Missy to discover for herself what the annotations meant, while also not divulging her true identity to Missy. (PROSE: The Liar, the Glitch and the War Zone) She demonstrated a playful sense of humour, labelling the Moment's interface "a Christmas cracker", and responding to Cass Fermazzi's mention of having childhood therapy with a dry "[don't] we all". (PROSE: The Day of the Doctor)

The Doctor claimed that she enjoyed making "trip[s] into the past" for research purposes, but knew to be cautious when making such trips. She retained the good nature of her predecessors, making a trip to 14th century Venice to rescue Antonia, and writing a note to chastise Missy for her lack of caution. (PROSE: The Liar, the Glitch and the War Zone). The Doctor took her devotion to the preservation of history seriously, describing herself and her companions as its guardians. In spite of her adamance, she would still show signs of distress if preserving history meant letting injustices go unpunished, such as the arrest of Rosa Parks as a result of contemporary racist laws. But when she saw first hand how Ryan and Yasmin were being treated by the people in Montgomery, she didn't hesitate to give them the chance of returning to the TARDIS. (TV: Rosa)

She retained the guilt demonstrated in her prior incarnations over the events of the Last Great Time War. Visiting Cass prior to her death, the Doctor expressed her regret over Cass' fate and noted that saving Cass was impossible as "[Cass] was too wrapped up in [her] timeline", demonstrating her continued respect for the Laws of Time. She was unwilling to alter her own personal timeline. (PROSE: The Day of the Doctor)

The Thirteenth Doctor was passionately against murder, trying her best to subdue her opponents in a non-lethal fashion, and going out of her way to stop the Stenza warrior Tim Shaw from killing and capturing humans on Earth (TV: The Woman Who Fell to Earth) and noted her disgust to Jack Robertson killing the mother spider. (TV: Arachnids in the UK) She also expressed distaste for the act even when committed by her allies. (TV: The Woman Who Fell to Earth) She also regularly voiced her dislike of weaponry, opting instead to use her intellect and environment to her advantage. She was strongly adverse to her allies using such methods, even in situations of dire peril. (TV: The Ghost Monument, Arachnids in the UK)

Like her immediate predecessor, she believed that "No one ever wins at war." (PROSE: The Good Doctor)

The Doctor expressed how, upon regenerating, she felt as if she were on the brink of death, only to be born again, a process which terrified her greatly. However, she countered she had to accept the subsequent change into someone new while ensuring everything she used to be, stayed with her in some capacity as well. (TV: The Woman Who Fell to Earth)

She used humour to defuse tension. (TV: The Woman Who Fell to Earth)

Much like her predecessor, the Doctor retained an anger toward racism. (TV: Rosa)

Despite her earlier statement to Grace and Graham that she would accept her new incarnation in Sheffield, (TV: The Woman Who Fell to Earth) the Remnant saw in her mind she was uncertain about her new body. (TV: The Ghost Monument)

Even when asserting her authority, the Doctor would reassure her friends' safety in a careful manner. (TV: The Ghost Monument) She considered her companions "fam". (TV: Arachnids in the UK)

She retained the somewhat absent-mindedness of her predecessor, tending to forget how many times she did something (TV: Rosa) or when she acted "weird". (TV: Arachnids in the UK)

Habits and quirks
Much like her ninth incarnation, the Thirteenth Doctor spoke with a northern accent. She also used "Oi" to get someone's attention. (TV: The Woman Who Fell to Earth)

Like her twelfth incarnation, she wrote things down with the marker in her sonic screwdriver. (TV: Rosa, Arachnids in the UK)

Resembling her tenth incarnation, she would consider good things to be "brilliant". (TV: Twice Upon a Time, Rosa) Also like him, she would often speak without thinking of other's feelings and then ask her companions if she was acting weird. (TV: Arachnids in the UK)

Similar to her fifth incarnation, the Thirteenth Doctor attempted to return her companions back home if they came with her by accident; (TV: The Ghost Monument) even having similar trouble trying to get the TARDIS to cooperate with doing so during early days. (TV: Rosa)

Early in this incarnation, the Doctor had some trouble adjusting to her new gender. (TV: The Woman Who Fell to Earth) She did not consider herself to be a man or a woman, "in the way that [humans] understand it". (PROSE: The Good Doctor) She told the temporarily dimensionally displaced TARDIS to "Come to Daddy", before correcting herself to say "Mummy", and following up with "whatever". (TV: The Ghost Monument) She was still having trouble getting used to people calling her "Ma'am" during a trip to Montgomery. (TV: Rosa) Eventually, she adapted to the change. (TV: Arachnids in the UK)

Though she could appreciate stopping for a quick snack, (TV: Rosa, Arachnids in the UK) the Doctor often ignored her companions' complaints about their hunger if she believed there were more pressing matters to attend to. (TV: Rosa)

The Doctor liked custard cream biscuits (TV: The Ghost Monument) and Yorkshire Tea. And disliked olives. (PROSE: The Good Doctor) For breakfast, she prefered cereal or croissants. (TV: Arachnids in the UK)

She liked the colour purple. (TV: Arachnids in the UK)

Skills
Using her nose, the Doctor could precisely time when her regenerative process would cause her to faint. Having recently regenerated, the Doctor was able to survive a great fall, and casually get up and spring to action, completely fine. However, the process caught up with her, eventually causing her to fall unconscious to nap and recharge. (TV: The Woman Who Fell to Earth)

She was also a skilled mechanic, able to make her own sonic screwdriver entirely from scrap on 21st-century earth. She could also build her own teleport to track the TARDIS, although mixed up the co-ordinations as she accidentally brought her friends with her and teleported into space rather than a planet. She also demonstrated astute detective skills, correctly determining a train driver died of shock rather than by a forceful attack. (TV: The Woman Who Fell to Earth)

The Doctor was knowledgeable about arachnids; knowing how strong their webbing can be, not to make sudden moves to avoid being instantly targeted as prey, and how to repel them using strong-smelling substances like vinegar. (TV: Arachnids in the UK)

Similar to the Eleventh Doctor, the Thirteenth Doctor showed an uncanny ability to change clothes at an astonishing speed, having taken merely moments to change into her selected outfit after deciding on it. (TV: The Woman Who Fell to Earth)

With the aid of Venusian aikido, the Doctor could use her pinky finger to paralyze someone without harming them by pressing on their neck, (TV: The Ghost Monument) and could throw someone over her shoulder with little difficulty. She was also swift and nimble, able to avoid being struck by a fist with ease. (COMIC: The Warmonger)

Appearance
The Thirteenth Doctor resembled a woman in her mid-thirties, possessing jaw-length blonde hair with dark roots, and hazel-coloured eyes. (TV: Twice Upon a Time) To her annoyance, she was shorter than her predecessor. (TV: The Woman Who Fell to Earth)

Lucy Wilson described her as a "beautiful woman". (PROSE: Avatars of the Intelligence) Patricia thought that the Doctor's face conveyed a constant, unashamed amazement. (PROSE: The Rhino of Twenty-Three Strand Street)

Clothing
After going clothes shopping with Ryan Sinclair and Yasmin Khan, (TV: The Woman Who Fell to Earth) the Thirteenth Doctor took to wearing a hooded, lilac-blue trench coat with dark blue interim and a rainbow pattern along the edges of it. (COMIC: The Many Lives of Doctor Who) She had to damage to coat to help history go undisturbed from Krasko's meddling, but had the damage repaired by Rosa Parks. (TV: Rosa)

Under her coat, the Doctor wore a T-shirt with rainbow stripes running across the chest, with the colouring coming in black, (TV: The Woman Who Fell to Earth) and burgundy. (TV: Rosa) Under her shirt, she wore a white jumper. (TV: The Woman Who Fell to Earth)

On her legs, she wore a pair of high-waisted teal blue culotte trousers, (COMIC: The Many Lives of Doctor Who) kept up by mustard yellow suspenders. (PROSE: Rose) For footwear, she wore blue striped socks with brown, laced-up boots. (COMIC: The Many Lives of Doctor Who) She sometimes wore a bum bag around her waist to carry her sonic screwdriver and psychic paper. (TV: Arachnids in the UK)

She also wore golden ringed ear cuffs at the top and at the lobe of her left ear. The top cuff was a series of eight joint stars, and the bottom cuff was in the shape of two hands holding each other. (TV: The Woman Who Fell to Earth)

First female Doctor
The Thirteenth Doctor is the first and,, only incarnation of the Doctor in the show's history to be played by a woman. Before Jodie Whittaker, though, the idea of a woman Doctor had been explored.

The idea that a female actor could take the role of the Doctor was first publicly introduced by John Nathan-Turner and Tom Baker in 1980. By Baker's suggestion, he told the press, "I certainly wish my successor luck, whoever he—or she—might be." Peter Davison was cast as the Fifth Doctor, but the idea remained alive, as in a Daily Star article from 29 July 1983, headlined as AFTER Dr WHO... Dr HER?, talking about Davison bowing out, Nathan-Turner said; "the hunt for a new doctor starts today and it's quite feasible it will be a woman". Colin Baker was eventually cast as the Sixth Doctor.

In 1986, creator Sydney Newman suggested that "at a later stage Doctor Who should be metamorphosed into a woman", offering Joanna Lumley as the potential candidate for the Seventh Doctor. and Dawn French were also mentioned. Eventually, Sylvester McCoy was cast in 1987.

By the time Whittaker was announced as the actor to follow Peter Capaldi, it was well-established, to viewers and within the Doctor Who universe, that the Doctor could be played by a woman.

Though a parody, The Curse of Fatal Death (1999) by Steven Moffat introduced another Thirteenth Doctor, played by Joanna Lumley. This Doctor, upon regenerating, immediately noted that she had "etheric beam locators" (calling back to an earlier gag where etheric beam locators had been confused for breasts). When Emma tells her that those are actual breasts, the Doctor says that she "always wanted to get [her] hands on one of these". At the end, she suddenly finds the Master attractive, and they walk off together, arms around each other's waists.

In 2002, the Big Finish audio Seasons of Fear features the Eighth Doctor telling his future/past enemy Sebastian Grayle, in his own first encounter with that character, that the Doctor is "not a glamorous woman at the moment", hinting that he could become such a thing in the future.

The Big Finish Doctor Who Unbound story Exile (2003), though not set in the prime Doctor Who universe, starred a female Third Doctor, played by Arabella Weir. The story tried to establish that, in this universe, suicide was necessary for a "sex-change regeneration", which was also considered a crime by the Time Lords. Later stories, particularly in the Steven Moffat era, would contradict the idea that changing gender during regeneration was anything out of the ordinary.

Prior to the massive comeback of the TV series in 2005, Jane Tranter wanted the Ninth Doctor to be the first female incarnation, played by.

In 2007, when David Tennant announced his intention to leave, the UK Resource Centre for Women in Science, Engineering and Technology (UKRC) wanted the next Doctor to be female, issuing a statement saying: "There is a distinct lack of role models of female scientists in the media and recent research shows that this contributes to the under-representation of women in the field. The UKRC believes that making a high profile sci-fi character with a following like Doctor Who female would help to raise the profile of women in science and bring the issue of the important contribution women can and should make to science in the public domain."

In 2010, The End of Time: Part Two had the Eleventh Doctor briefly think he had regenerated into a woman, immediately post-regeneration. He quickly realised that he was mistaken, on finding his Adam's apple.

In 2011, Neil Gaiman's The Doctor's Wife was the first to make direct reference to a Time Lord changing gender through regeneration. The Doctor talks of the Corsair, a "fantastic bloke", who was also a "bad girl" in a couple of their incarnations.

In 2013, The Night of the Doctor had the Sisterhood of Karn offer the Eighth Doctor the choice of "man or woman", for his approaching regeneration. However, the novelisation of The Day of the Doctor revealed that the elixir given to the Doctor was just lemonade and dry ice, so the offer is almost rendered a moot point.

That year, the idea of a female Twelfth Doctor gained a media presence. The Guardian offered up their own suggestions for the role.

In 2014, Steven Moffat introduced audiences to, revealed in Dark Water to be the first female incarnation of the Master. Missy was a recurring character in series 8, 9, and 10.

In 2015, Hell Bent showed audiences the regeneration of the General, from a male to a female incarnation. While not the first such regeneration depicted, it was the first to take place on-screen. Just eighteen days before the episode aired, Big Finish audio story The Black Hole had its own male-to-female regeneration scene.

In 2016, Enemy Lines, another Big Finish audio, showed the first female-to-male regeneration.

2017's World Enough and Time included a rooftop conversation, between the Twelfth Doctor and Bill, in which he's only "fairly sure" that his first incarnation was a man, as it was a long time ago. The Twelfth Doctor here claims that Time Lords are "beyond [the] petty human obsession with gender and its associated stereotypes".

The same year, the audio story The Conscript included a conversation between the Eighth Doctor and a Time Lord soldier, where the Doctor stated that he was a "he, for now at least".

Appearances prior to her first full story
The Thirteenth Doctor is unique amongst her previous incarnations by having appeared multiple times in the expanded media before her official television debut in The Woman Who Fell to Earth.
 * Like most incarnations of the BBC Wales series, she appeared in a specially-made teaser trailer in the run-up to series 11.
 * She was featured in the narrative poem The Death List from the collection Now We Are Six Hundred, with an illustration by Russell T Davies.
 * Postcards from the Thirteenth Doctor to Doctor Who spinoff characters were discussed and depicted in the Lethbridge-Stewart short story When Times Change... (printed with The Two Brigadiers); the Iris Wildthyme short story A Lady Doctor?; and the City of the Saved short story Postscript in Stranger Tales of the City.
 * She was mentioned as appearing with her other incarnations in archive footage during Avatars of Intelligence and Rose.
 * She made an extended speaking cameo in The Liar, the Glitch and the War Zone, though her identity was only revealed at the end of the story.
 * She made a surprise appearance in Chapter 13 of The Day of the Doctor.
 * Her costume made its debut in the invalid comic story And Introducing....
 * The first official trailer featuring this incarnation was put forward as a part of the major press debut of the series 11 team at San Diego Comic-Con 2018.