Bill Potts, played by Pearle Mackie, is a young, gay woman who works in the cafeteria, serving chips, at St. Luke’s university. She regularly crashes lectures that are given by The Doctor, even though she is not a student at the university. After discussing her reasons for attending his lectures, The Doctor offers to tutor Bill.
When she first encountered the Doctor, Bill was working as a canteen assistant at St Luke’s University, seemingly destined for an unprivileged life. When free from work, she attended some of the Doctor’s lectures at the university. The Doctor saw her unfulfilled potential and invited her for a series of personal tutoring sessions.
Following an encounter with a time-travelling puddle that was piloted by her friend Heather, Bill discovered who the Doctor really was — an alien time-traveler, guarding a secret vault beneath the university campus. The Doctor invited her to join him on a journey through space and time.
On her adventures with the Doctor and Nardole, Bill traveled to a human colony planet and visited the last of the great frost fairs. She faced the vacuum of space and saved the Earth using the memory of her mother. She also learned that the Doctor was trying to rehabilitate his old Time Lady friend Missy. (TV: The Eaters of Light)
When accompanying the Doctor on his test to see if Missy could be good, she was fatally shot on a Mondasian ship by Jorj. She was then converted into a Cyberman against her will. (TV: World Enough and Time)
Bill was born around 1991. (TV: The Pyramid at the End of the World) Her mother died when she was young, so she was brought up by a foster mother called Moira. (TV: The Pilot)
Later in life, Bill served chips at St Luke’s University in Bristol, and — despite not being a student — attended some of the Doctor’s lectures. Noticing her potential, he became her personal tutor.
During Christmas 2016, Bill mentioned to the Doctor that she was “supposed to look” like her mother, but, as her mum rarely had any picture taken, Bill didn’t really knew if she looked like her. When she went to the flat where she lived with her mother, Moira told her she had found a box with pictures of Bill’s mum. On one of the photos, Bill could see the Doctor’s reflection.
Over the course of her tutoring in 2017, Bill developed a crush on another student, Heather, who showed her a puddle that cast a reversed reflection. Bill asked Heather not to leave without her. As a result, when Heather was taken over by the puddle, she followed Bill home, so as not to leave without her.
Bill went to the Doctor’s office, and then he brought her into the TARDIS. He tried to outrun the water creature, and finally traveled to a war zone in the Dalek-Movellan War. Bill realized she was being pursued as Heather had promised not to leave without her. On the Doctor’s advice, she released Heather from her promise.
The Doctor took her back to the university, where Bill expressed regret at having turned down Heather’s offer, with the Doctor telling her it was unlikely they would ever see each other again. When Bill knowingly looked at the TARDIS, the Doctor realized what she was suggesting and made her stand close to him, intending to wipe her memory of these events, but she convinced him not to. He then agreed to take Bill with him on his travels, acknowledging that they might run into Heather one day. (TV: The Pilot)
With The Doctor
The Doctor took Bill to visit a human colony in the far future lying to Nardole that he was just transporting the TARDIS back to the office. When the Doctor discovered the Vardy robots had killed the set-up team on the colony, the pair escaped the colony, running from the Vardies and Emojibots, but the Doctor ran back in to attempt to destroy the base for the sake of the coming settlers. The Doctor wanted Bill to stay behind, but Bill followed him, believing that the reason the Doctor kept the TARDIS in the shape of a police box and why he didn’t ask for help was because he was the helpline. The Doctor showed her that the Vardies were actually a part of the building and had constructed the colony using themselves. He had Bill give him directions to the main power center using a map before Bill realized he had memorized the schematics and was keeping her at the map to keep her out of trouble. Bill was horrified to discover the colonists were the last humans in existence after Earth was evacuated.
As soon as the Doctor had wired the ship the city had been built around to blow, Bill emerged with a boy called Praiseworthy. The Doctor realized that the colonists had already arrived in hibernation waiting for the ship to wake them up, and entering the ship woke the colonists. The Doctor stopped the bomb, and the pair deduced that the Vardies had been built to sustain happiness and had come to view grief as a plague.
The Doctor rebooted the Vardies, erasing their memories of the humans, before beginning diplomatic negotiations between the humans and Vardies. He then tried to return to the university just after they left, but when he and Bill exited the TARDIS, they discovered they were outside in winter with an elephant in front of them. (TV: Smile)
On exploring London in 1814, The Doctor and Bill attended the last Frost Fair on the River Thames before noticing strange lights under the ice. Bill witnessed firsthand the death of a little boy when he was sucked under the ice and was horrified and disgusted when the Doctor seemed to care more about retrieving his sonic screwdriver that the boy had stolen. Bill challenged the Doctor demanding to know whether he had ever killed anyone to which he confirmed saying that he did not have the luxury of for outrage as he was 2000 years old. Bill befriended the urchins who had originally stolen from them and chose to cooperate with the Doctor. Their investigation led them to Lord Sutcliffe with the Doctor warning Bill to let him do the talking as it required a diplomatic approach. After Sutcliffe made racist remarks towards Bill, however, the Doctor punched him in the face. Later Bill agreed with the Doctor to set the Monster in the Thames free surprised when it wasn’t headline news in the present day. (TV: Thin Ice)
Bill visited the mining station named Chasm Forge after the TARDIS received a distress call to visit it. As oxygen was regulated and the Tardis exterior air shell was being removed, Bill had to wear a smartsuit that provided her with a force field which held air in. When entering an airlock which required a solid physical helmet, Bill’s suit automatically took her helmet off. This meant Bill was exposed to the vacuum of space. The Doctor later gave her his helmet, at the cost of his sight. (TV: Oxygen)
After viewing an email from his virtual counterpart, the Doctor called Bill asking if she knew a person called Penny. Bill did, but deemed her “out of [her] league”. The Doctor assured her she wasn’t and told her to call Penny that night as he had a “feeling [they were] going to be very busy”. (TV: Extremis)
Bill went on a date with Penny and told her about the virtual world the Doctor had since told her about. Penny was disbelieving but the date was going well until armed soldiers and the Secretary-General of the UN arrived to collect Bill and take her to see a pyramid that had appeared over night. On board the Doctor’s President plane, Bill tried to convince him to come and help with the pyramid but he denied until he realized he didn’t have a choice as he was already on the plane.
At the pyramid, Bill was confused when Nardole was ‘updating’ the Doctor on what was happening in front of them as the latter approached. Her phone, like every other device with a clock, received a message saying 23:57pm as the Monks started a countdown to the end of the Earth, demanding surrender. The Doctor, Bill and Nardole then took the Heads of the American, Russian and Chinese armies and had them strike the pyramid in a coordinated attack.
The Monks stopped the attacks with ease and expressed they were ready to talk. Inside, the Monks revealed that Earth would be dead in a year’s time if the planet did not consent to the Monks.
The Doctor was against consenting to something he didn’t understand though Bill and the others were more willing. However the Monks explained that Love was needed in consent, burning the Secretary-General when he consented out of Fear.
Back on board the President plane, the army heads agreed not to fight one another believing that they would be stopping World War III, but this failed to revert the clocks. Bill compared the need for consent as to inviting vampires into a person’s home. She also theorized a bacterial possibility and the Doctor had them all google possible problems. However, Bill and the army heads were considering surrendering Earth to ensure the planet survived, unwilling to put such risk especially when the clocks moved to 23:58pm.
As the Doctor and Nardole deduced the problem as a biological component released in a lab, Bill and the army leaders went to the Pyramid as the countdown reached 23:59pm. Inside, the army leaders were burned for consenting out of Strategy. Bill went to leave when the Doctor managed to solve the problem and the countdown began to go backwards. However, when the Doctor could not leave due to being blind and unable to spin the combination lock, Bill returned and consented to The Monks have authority over the Doctor in return for his sight being restored. Before the Monks accepted her ‘pure’ consent out of Love, she told the Doctor to save her planet. (TV: The Pyramid at the End of the World)
Bill was reunited with Nardole during the Monk’s reign over Earth. She had been away from Nardole and the Doctor for six months since their last adventure.
Nardole located Bill and helped her find the prison hulk where he believed the Doctor is making his broadcasts and is captive there. The Doctor told Bill he was cooperating willingly with the Monks, believing that humanity was doomed without their guidance. Bill became distraught and shot the Doctor with a gun she toke from one of the SWAT troops, and appears to begin regenerating, but quickly stops. The entire scenario is revealed to have been a test by Nardole, the Doctor and the team, to make sure Bill was not under the influence of the Monks.
At the university where the Doctor and Bill work, they enter the Vault to talk to Missy, who says she has encountered the Monks before. She confirmed the Monks maintain control by broadcasting a signal containing the false history to their subjugated victims via the numerous statues they have built across Earth, enabled by a psychic link established through the person who originally gave “consent”; Missy claimed to have defeated them during her own encounter by killing that individual. She implies that Bill must die as the one who gave consent on Earth.
Bill accepts her fate but the Doctor is determined for another solution. Along with Nardole and the commandos, they infiltrate the Monks’ pyramid in London so that the Doctor can hijack their broadcast with his own mind to break the psychic transmission. In the central chamber, the Doctor attempted to link his mind to the controlling Monk, who after a struggle overpowered the Doctor. Bill intended to sacrifice herself, linking her own mind to the Monk’s despite the Doctor’s protests. The Monks’ broadcast was replaced with images of Bill’s mother, which the Doctor recognizes is a strong and loving memory in Bill’s mind. Humanity woke up from the Monks’ lies and revolted against them. The Doctor, Bill, and Nardole watched as the Monks abandoned Earth. Sometime later, the Doctor and Bill find that most of humanity had no recollection of the Monks. (TV: The Lie of the Land)
Bill and Nardole, watched over by the Doctor, became Missy’s companions on a test trip to determine whether she could reform from her evil ways. While surveying the colony ship they were on, Bill was mockingly called the “exposition” and “expendable” by Missy. Bill was mortally wounded by a paranoid technician who was the only one left of his crew, due to her being human. Unable to save her, the Doctor allowed her to be taken by medical figures who had come from the lower levels of the ship as he understood were capable of healing her. He left a message in her subconscious for the moment she awoke: “wait for me”.
After several months for her, she awoke with a cybernetic heart in a hospital. Due to the spaceship’s proximity to a black hole (causing time dilation within it) Bill was forced to wait years for the Doctor and in the meantime made friends with a man named Razor. Razor allowed her to watch the Doctor and the others upstairs, though time passed extremely slowly; by the time the Doctor raised an eyebrow, a week passed for Bill. Razor also took her outside the hospital once, explaining how everyone had to be converted to survive given the time differential with the upper levels. In the end, Razor, in reality the Master in disguise, deceived her, and Bill suffered cyber-conversion alone. (TV: World Enough and Time)
Bill managed to reject the Cyber programming enough to help save the Doctor from another Cyberman and carry him to safety after the ship Nardole piloted crashed on level 507. She was turned into an Sentient oil creature. After she took the Doctor to the TARDIS, she went travelling with Heather. (TV: The Doctor Falls)
Bill was very smart and very inquisitive. She asked questions that most people didn’t ask and came to conclusions in a different way than other people normally did. She loved science fiction and was open to the idea that the concepts it proposed were real and affected the lives of those around her. When Heather introduced her to a strange puddle, she was open to the idea of alien lizard possession, no matter how preposterous the Twelfth Doctor found it. She was also easily able to figure out that the Doctor intended to wipe her memory when he tried to put her hands on her head, and even called out the Doctor for thinking she was stupid enough to fall for it. (TV: The Pilot)
Bill was also rather bold, hating the idea of being spoken to in a sexist manner and having to withhold her opinion due to racial stereotypes of the 19th century. When Lord Sutcliffe demanded she submit to him, Bill merely sneered at him. She also learned to understand the need to not dwell on matters that angered her as the Doctor taught her there simply wasn’t time to waste on such matters. (TV: Thin Ice)
Bill was interested in girls. (TV: Knock Knock) She had a crush on a girl who attended the Doctor’s lectures, and developed an interest in another young woman, Heather. (TV: The Pilot)
Despite having never met her mother, Bill invented an imaginary version of her which she spoke to for personal comfort. (TV: Oxygen, The Lie of the Land) According to Bill, this version always told her “with some people you can smell the wind in their clothes”, a saying Bill made up based on what she thought her mother would say. (TV: The Pilot)
Bill was extremely bright and quick witted, able to perform well in the Doctor’s university assessments with his private tuition in the field of science, and impressed him enough before had that he saw potential in her. She was also able to deduce complex puzzles with only some prompting from the Doctor, notably that the puddle in the ground was not reflecting as a mirror and that the damaged cement was actually scorch marks of the ships, (TV: The Pilot) and that the lights, which she perceptively noticed, under the ice in the Thames were organic rather than artificial. (TV: Thin Ice) Bill also deduced the TARDIS granted her the ability to speak different languages, (TV: The Eaters of Light) and that the patients in the hospital were in severe pain despite “Razor” trying to convince her otherwise. (TV: World Enough and Time)
She could even notice things the Doctor overlooked, such as the strangeness that a grown man would root through grass and trees for bugs, or that he wasn’t old enough for the Doctor’s theory to make sense. She was also rather brave, leading her group of flat mates when they were scared. (TV: Knock Knock) She further displayed bravery as she volunteered to combat the oncoming Cyberman from floor 1056 in her cyber form despite the Doctor implying it’s technology would be more formidable than her own and stayed to combat the army of multiple fully evolved Cybermen despite knowing full well she would die in the conflict. (TV: The Doctor Falls)
When transformed into a Cyberman, she managed to retain her free will despite being fitted with an emotional inhibitor. The upgrade prolonged her lifespan (though it slowed her down to mere walking speed) and also gave her a cybernetic blaster on the handlebars on her headpiece. Using said blaster by channelling anger, she could blast a gaping hole in a barn and a concrete wall, incinerate another Mondasien Cyberman and could combine with the Master’s modified Laser screwdriver to disable a fully evolved Cyberman. She also retained the ability to cry, a gift her friend Heather granted her to be able to find her. (TV: The Doctor Falls)
Bill was a young woman with dark skin and afro-textured hair. (TV: The Pilot, et al.) According to the Doctor’s sonic sunglasses, Bill was female, was 26 years old by the time of the Monks’ invasion, weighed 130.2 pounds, and measured 167.7 cm in height. (TV: The Pyramid at the End of the World)
She didn’t like her face because it was “always doing expressions [when she was] trying to be enigmatic”. (TV: The Pilot)
When mortally wounded by Jorj, she was partially cyber converted, given a cybernetic chest-unit. She was also eventually converted into a Cyberman, subsequently looking like one. (TV: The Doctor Falls)