The Doctor

"Hello! I'm the Doctor!"

- The Doctor's most frequent greeting.

"Hello? Who's there? Hello?"

- First Doctor's first lines

"Slower... SLOWER! Concentrate on one thing... ONE THING!"

- Second Doctor's first lines

"Shoes... I must find my shoes..."

- Third Doctor's first lines

"Human history... I tell you Brigadier, there's nothing to worry about. The Brontosaurus is large and placid... and stupid."

- Fourth Doctor's first lines

"Ah... You've come to help me find the Zero Room. Welcome aboard. I'm The Doctor... Or will be if this regeneration works out!"

- Fifth Doctor's first lines

"You were expecting someone else?"

- Sixth Doctor's first lines

"Oh no, Mel... Ah, that was a nice nap! Now down to business... I'm a bit worried about the temporal flicker in sector thirteen... There's a bicentennial refit of the Tardis to book in... I must just pop over to Centauri Seven and then perhaps a quick holiday... Right, that all seems quite clear, just three small points, where am I? Who am I? And who are you? The Rani! Stay back!"

- Seventh Doctor's first lines

"Who am I? Who am I? Who... Am... I?"

- Eighth Doctor's first lines

"Doctor no more"

- War Doctor's first lines

"Run!"

- Ninth Doctor's first lines

"Hello! Oka- New teeth. That's weird... So where was I? Oh, that's right... Barcelona!"

- Tenth Doctor's first lines

"Legs! I've still got legs! Good. Arms, hands. Ooh, fingers. Lots of fingers. Ears? Yes. Eyes: two. Nose... I've had worse. Chin... blimey! Hair... I'm a girl! No! No! I'm not a girl! And I'm still not ginger! There's something else... Something important, I'm... I'm... I'm... Crashing! Geronimo!"

- Eleventh Doctor's first lines

"Kidneys! I've got new kidneys! I don't like the colour."

- Twelfth Doctor's first lines

The Doctor is the titular main protagonist of the popular Sci-Fi TV show Doctor Who as well as the many comic books and spin-offs spawned from its success. He is a human-like alien who protects the Earth, along with countless other worlds, throughout time and space, from such menaces as the Daleks and The Master. Unlike the rest of his race of time travellers, he uses time travel to interfere with events, which is forbade by his race, in an effort to protect civilizations from a variety of threats. He is famous for his time traveling ship the TARDIS, his sonic screwdriver and the ability to regenerate into a new form with a slightly different personality if he is either injured or on the verge of death, though his species is normally able to regenerate only twelve times. To date, the Doctor has thirteen regenerations, the thirteen being given to him along with a new set of twelve regenerations.

He has been portrayed by thirteen different actors over the course of the series. His previous portrayer Matt Smith, announced that he would leave the series after the 2013 Christmas Special, The Time of the Doctor. His most recent portrayer, Peter Capaldi, took over the role at that point. However in the 2017 Christmas Special, the Doctor will regenerate into a female and will be portrayed by Jodie Whittaker.

Despite being the protagonist, there have been some episodes of the series where the Doctor is a supporting/minor character and instead one of his companions or a guest character takes the role of protagonist for that episode.

History
The Doctor is an alien from the planet Gallifrey, a member of a race known as the Time Lords. He travels through time and space in a spacecraft called the TARDIS, frequently with human companions, averting any crisis he comes across using science, technology, and wit. As a Time Lord, he has the ability to regenerate, or change his appearance and personality whenever he is injured or on the verge of death. Although the series is titled Doctor Who, this is not the character's name: he is only ever referred to as The Doctor and his real name remains mysteriously unknown. From his ninth to his eleventh incarnation, he was believed to be the last surviving member of the Time Lords, and was under the impression that he, during his War Doctor incarnation, had destroyed Gallifrey in order to end a devastating Time War against the Daleks. He later learned differently.

The Time Lords of Gallifrey imposed a limit as to how many regenerations one may have before final death - twelve changes, or thirteen incarnations. Due to the "War Doctor" not accepting the name Doctor, and the Tenth Doctor undergoing an aborted regeneration at one point, the Eleventh Doctor believed himself to be the last incarnation. The Time Lords, however on the request of Clara Oswald, bestowed upon him a new regeneration cycle, allowing him to ultimately transform into the Twelfth Doctor (technically the Doctor's fourteenth incarnation).

Abilities

 * Regeneration: When a Time Lord is dying - either due to old age or mortal injury - they are able to use a process called regeneration. Regeneration is a process in which all the cells in the body are replaced with new ones, with the ultimate result being the Time Lord having a completely new appearance. Even though the Doctor has changed numerous times, he still remains the same person inside and remains a force for good, if neutral, even though his priorities, personality and memories sometimes change, due to the fact that regeneration alters his brain chemistry as well. The regeneration process has been portrayed as either a simple fade between two incarnations, a glowing effect that revealed the next incarnation, or one incarnation morphing into the next. In recent portrayals, it has been portrayed as the incarnation generating or radiating a gold, orange or even white fire-like energy while transforming into the next incarnation. Oftentimes, the regeneration energy manifests in an explosive discharge which could damage or destroy anything or anyone around it. The brunt of the discharge is directed through the hands and head and could be made more powerful and violent if more energy was built up through stalling the process. It was also made violent and even accompanied by a powerful shockwave if a new set of regenerations was given. The Doctor has been able to generate this regeneration energy at will in fiery wisps or as a yellow light, using it to heal non-life-threatening injuries and somewhat stall certain terminal conditions. However, all Time Lords have a finite amount of this energy, which means using it in this manner could be lessen the ability to regenerate. Eventually, the Doctor will lose the ability to regenerate after twelve or thirteen regenerations and incarnations, though he was later given a new set of regenerations by the Time Lords, the process of which caused a giant discharge of regeneration energy and a shockwave that expanded several miles. The regeneration process could also cause a brief period of emotion or mental instability, erratic behavior, mood swings, random spasms, lack of motor skills, confusion, memory loss, and unconsciousness, which is called "regeneration trauma". This period lasted for hours and also allowed the Doctor temporary abilities, such as a healing factor and superhuman strength, though which ability he receives is highly random. However, some regenerations happened without any period of trauma, such as the Eighth Doctor's transformation into the War Doctor.


 * Superhuman Strength: He possess above-average strength, as he once broke down steel doors, chopped a brick in half and ripped a stone arm off a statue. This, however, is a random occurrence and an immediate after-effect of his regeneration, as such abilities only last 15 hours after the occurrence.


 * Superhuman Senses: He is capable of sensing time disturbances and perceive all possible timelines, as well as senses attuned to gravity, spatial location, and acceleration/speed. As well as having smell (sharp enough to identify the atmospheric composition), taste (can identify an age and chemical composition of an object by licking), hearing, and eyesight (can read a name-tag from several hundred yards away, as well as see in the night like a cat) that is superior to humans. He is stated to be able to feel a planet's rotations while on it.


 * Superhuman Durability: While the level of his durability is undefined, he has been able to survive harsh conditions which include (but not limited to), the low-pressure and coldness of space without a suit (though he still needs air), subzero temperatures, extreme heats of at least 525 degrees Fahrenheit, multiple electric shocks, X-ray radiation, and falls from hundreds of feet, though the Fourth Doctor was injured by such fall to the point where he regenerated into his Fifth incarnation. He is also more resilient to radiation, allowing him to be barely harmed by an x ray machine's radiation, though it was 500,000 rads of radiation was what caused the Tenth Doctor to regenerate into the Eleventh in what seemed to be hours after exposure. He is also resistant to temporal disturbances, allowing him to be fully aware of any changes to time, especially if he is at the epicenter of this change, such as when his supposed death at Lake Silcencio was averted and all of reality began to collapse. The Doctor himself ended up in Ancient Rome, fully aware of what happened. He is immune to alcohol or wine. Normal sleep-inducing drugs take twice as long to take their effect on him as it does a normal human being and are not able to keep him asleep for long.


 * Omnilingualism: He is able to speak and understand virtually every language in existence. Although his ship, the TARDIS, is said to translate for his companions, the Doctor possesses this ability on his own. He can even communicate with some animals, such as cats and even dinosaurs.


 * Enhanced Lung Capacity: His alien respiratory system allows him to hold his breath for 20 minutes, remain buoyant in water and survive strangulation, as it can be bypassed briefly. His body also has lower need for oxygen and can handle high levels of carbon dioxide that would kill a human. He can even hold his breath in the vacuum of space and survive without a suit for some time.


 * Superhuman Endurance: Needs only an hour of sleep a day, and tires much less than a human.


 * Superhuman Reflexes: Is stated by the Doctor himself to have reflexes ten times faster than a human being. Is proven when he was able to move across a giant spinning fan.


 * Superhuman Healing: Besides regeneration, Time Lords heal much faster than humans, as well as a special ability to go into a healing coma which accelerates the healing process even faster. In the span of 15 hours after regeneration, he can regrow entire body parts and be seemingly immune to crippling pain. While the regeneration process started, other minor injuries can heal instantly.


 * Superhuman Intelligence: The Doctor is vastly smarter and think faster than most beings in the universe. He has an almost universal knowledge of nearly every species in the universe, as well as an expert on technology, chemistry, physics, mathematics, history, non-human biology, genetics and nearly every field (except ironically human medicine, as he is says he is not a medical doctor).


 * Psychometric Telepathy: As a Time Lord, The Doctor is capable of using telepathy and related abilities (e.g. memory control and hypnosis), via physical contact, usually by touching a person's head. He once used a headbutt to make a man named Craig know about his alien origins and incarnations instantly. His psychic senses allowed him to use a telepathic satellite network to channel all of humanities hope when they all spoke and thought his name at the same time, resulting in him being able to recover completely from being aged into a old man and then into a deformed and diminutive creature. While using this accumulated psychic energy, he was glowing with a fiery blue aura that shielded him from energy bolts, allowed him to make the cage he was locked in vanish, made him able to fly and levitate, and even telekinetically disarm an opponent. However, he only had these powers for a few minutes before returning to normal.


 * Longevity: The Second Doctor stated that Time Lords can "live forever, barring accidents." Thanks to regeneration and his own natural longevity, the Doctor has lived for many centuries -- his first incarnation alone existed for over 450 years. Time Lords, in general consider 700 years to be middle ages, though its unknown if that is for just one incarnation or their entire lives. By the time of the Seventh Doctor he has stated he is approximately 956 years old. However, the Ninth Doctor he says he has forgotten his age and restarts from 900 years, while the Eleventh Doctor guessed that he was 1,200, though he also said he had forgotten. By the time he has regenerated into the Twelfth Doctor he can be estimated to be at least 2,000 years old, if not older.

First Doctor


"One day, I shall come back. Yes, I shall come back. Until then, there must be no regrets, no tears, no anxieties. Just go forward in all your beliefs, and prove to me that I am not mistaken in mine."

- The First Doctor's iconic farewell to Susan.

The First Doctor was played by William Hartnell.

The First Doctor was the youngest incarnation of the Doctor, but had the most aged physical appearance, having grown old through a natural lifespan. This Doctor was an unreadable, guarded figure who was, at first, slow to trust newcomers who learnt of him. This Doctor was often irascible. He made his anger obvious. He was protective of the young women he took on as companions; they reminded him of his granddaughter, Susan, his very first companion. This Doctor was a brilliant, often short-tempered scientist and keen strategist. He used his signet ring to help get himself through ordeals due to his physical age impeding him. He stole a TARDIS and took his granddaughter with him, joyriding through all space and time, without a clue as to how to drive the thing.

He played deadly games with the Celestial Toymaker, he fooled Roman emperors, Mongol warlords and French revolutionaries, and he foiled each and every machination of the Daleks. After preventing the Cybermen from absorbing the Earth's energy and with his body “wearing a bit thin”, the First Doctor changed into his second incarnation.

He will reappear in the 2017 Christmas Special "Twice Upon a Time" where he will team up with his twelfth incarnation. He will be portrayed by David Bradley.

Second Doctor
The Second Doctor was portrayed by Patrick Troughton.

The Second Doctor, in contrast to his preceding incarnation, was warm and wise. He was as surprised and frightened of alien menaces as those who faced them with him. He had a knack for manipulation and deception. His predecessor would refer to him as a "clown" due to his bumbling nature. He loved tootling on his recorder and carried around a 500-year diary, trying to record his travels, but ended up discarding it. He wore a big fur coat that dwarfed him, tying it closed with twine. A "cosmic hobo" with a Beatles-esque mop of black hair, he was forever getting himself in and out of trouble. The Second Doctor was forced to undergo regeneration - essentially submit to execution - by the Time Lords as punishment for interfering with the affairs of many worlds.

Third Doctor
The Third Doctor was portrayed by Jon Pertwee.

The Third Doctor was a more dashing figure than his predecessors. He was described by his first incarnation as a "dandy". He had a penchant for inventing gadgets and was skilled at martial arts, particularly Venusian aikido, and owned a vintage car named Bessie. His initially contentious relationship with Brigadier Lethbridge-Stewart softened into a close friendship during his exile on Earth, lasting through his future regenerations, despite not always agreeing with his actions. He also displayed great affection for his female companions, particularly Jo Grant. He was a gallant action hero who was very protective of his companions. Radiation exposure from visiting Metebelis III led to his regeneration.

Fourth Doctor
The Fourth Doctor was portrayed by Tom Baker.

The Fourth Doctor was more eccentric than his previous incarnations and was the first to seem "young." Rarely without his very long scarf, he always carried jelly babies in his pockets, using them as bluffs, gifts and distractions—and occasionally snacks. He relied on his considerable charm, luck, and experience to get through bad situations. Although he retained his fondness for Earth, he ended his regular association with UNIT almost immediately upon his regeneration and only occasionally returned to the planet. However, he had not properly resigned from the position. He hated to work and preferred travelling but liked history. He usually travelled with only one companion at a time, except at the start and near the end of his life. He regenerated as a result of a fall suffered during an encounter with the Master; on this unique occasion a faceless "in-between" incarnation of the Doctor known as the Watcher assisted in the regeneration.

Fifth Doctor
The Fifth Doctor was portrayed by Peter Davison.

The Fifth Doctor was fond of cricket and wore a stick of celery on his lapel. After a difficult regeneration, this Doctor displayed energy, compassion and innocence not seen in his predecessors. His character was very human and vulnerable. Like them, he used improvisation as the best way out of a tricky situation. The Fifth Doctor was the first incarnation since the First Doctor to go "hands free" and forgo the usage of a sonic screwdriver after having it destroyed. He occasionally wore glasses, even though he didn't need them; he only wore them to make himself look clever. (TV: Time Crash) He was the first Doctor to sacrifice himself for another, when he and Peri Brown were dying from Spectrox toxaemia; with only one dose of the antidote available, he gave her the cure rather than taking it himself.

Sixth Doctor
The Sixth Doctor was portrayed by Colin Baker (not related to Tom Baker.)

The Sixth Doctor was a grandiose and eloquent incarnation. He sported a multi-coloured wardrobe that looked like it was designed by Christian Lacroix; it was often commented upon, occasionally leading to him being mistaken for a jester. This Doctor loved a good quote, often making one he deemed appropriate during an adventure. He also proved to have great acting skills on numerous occasions. His manic personality and acerbic wit could shade into moral passion, but his lack of concern for little things disgusted his companions. He was also capable of violent action, much more so than his past lives, even seeing logic in murder. Like the Fourth Doctor, he spent most of his travels with a single companion.

The circumstances of his regeneration are unclear; he begins to transform after the TARDIS is snatched mid-flight by an evil Time Lord known as the Rani.

Seventh Doctor
"There are worlds out there where the sky is burning, and the sea's asleep, and the rivers dream; people made of smoke and cities made of song. Somewhere there's danger, somewhere there's injustice, and somewhere else the tea's getting cold. Come on, Ace. We've got work to do."

- The Doctor in "Survival."

The Seventh Doctor was portrayed by Sylvester McCoy. The Seventh Doctor had a voice touched by a Scottish burr. A keen strategist and scientist and especially early in his life, lighthearted, this Doctor was a planner of the highest order. Embracing the complexities of time travel and his ability to manipulate and plan for the future, the Seventh fully embraced his role of Time Lord, even if it risked alienating his companions. However, he wished to help heal psychological scars which his companions suffered from. He spent most of his later travels with a single companion. The Seventh Doctor "died" as a result of a botched medical procedure (a human doctor not being aware of his double-circulatory system).

Eighth Doctor


"I’m a Time Lord in a realm where the term is meaningless. My pain has been infinite. Eight lifetimes worth. I left my world to travel, to experience the universe, but there’s been a price for my freedom. Worlds, I’ve seen subjugated or destroyed. Friends I’ve lost. Don’t tell me you’ve tapped yourselves in my mind and you can’t see that. Come on, there’s something else. Some other reason for all this… You’re frightened of me, aren’t you? You think I’ll destroy you."

- The Eighth Doctor, in The Twilight Kingdom.

The Eighth Doctor was portrayed by Paul McGann.

The Eighth Doctor showed a romantic and sensitive side not displayed by previous Doctors. Less morally flexible than his immediate predecessor, the Eighth Doctor suffered from bouts of amnesia, first after his regeneration and again after Gallifrey was destroyed following the War with the Enemy (but was later recreated). Unlike other Doctors, the Eighth spent his travels crossing not only time but into parallel universes and alternate timelines, making his personal timeline hard to piece together.

This Doctor refused to take part in the Time War, but after sustaining mortal injuries in a spaceship crash, he was given the rare opportunity to choose the form of his next life, and he chose to be a warrior in order to fight the war.

War Doctor
"Time Lords of Gallifrey, Daleks of Skaro. I serve notice on you all. For too long I have stayed my hand. No more. Today you leave me no choice. Today this war will end. No more. No more."

- The War Doctor announces his intent to end the war using the Moment.

The War Doctor was portrayed by the late John Hurt.

The War Doctor's incarnation was specifically chosen to be that of a warrior in the Last Great Time War and the regeneration was aided by the Sisterhood of Karn. His later incarnation stated that his actions broke "the promise" of the "name of the Doctor." As such, although the label "War Doctor" has been ascribed to him, he did not, in fact, accept the name Doctor (and as such he is not counted in the numbering of incarnations). Shortly before regenerating due to old age, the War Doctor encountered his Tenth and Eleventh incarnations and, between them, they actually came up with an option that allowed the Time War to end without destroying Gallifrey. Due to the laws of time, however, the War Doctor was unable to remember this, and thus his following incarnation believed that he destroyed Gallifrey, and as such "disowned" the War Doctor incarnation.

Ninth Doctor
"Do you know like we were sayin'? About the Earth revolving? It's like when you're a kid. The first time they tell you that the world's turning and you just can't quite believe it 'cause everything looks like it's standin' still. I can feel it. The turn of the Earth. The ground beneath our feet is spinnin' at 1,000 miles an hour and the entire planet is hurtling around the sun at 67,000 miles an hour, and I can feel it. We're fallin' through space, you and me, clinging to the skin of this tiny little world, and if we let go... That's who I am."

- The Ninth Doctor to Rose Tyler.

The Ninth Doctor was portrayed by Christopher Eccleston.

The Ninth Doctor considered himself the sole Time Lord survivor of the Time War. He displayed much of the playfulness of his previous incarnations, but was emotionally and psychologically scarred by the war and his role in it, which sometimes resulted in a detachment that was interpreted by some as cruelty. When asked about his voice and accent, he responded, "Lots of planets have a North". He cared deeply for Rose; he began to heal thanks to her. Similar to his first incarnation, this Doctor liked to tease others by pretending not to remember names. He also made dry jokes when facing danger or to diffuse tension. By all accounts, this incarnation was very short-lived compared to the others; he regenerated after absorbing the energy of the Time Vortex in order to save the life of his companion, Rose.

Tenth Doctor


"I'm the Doctor. I'm a Time Lord. I'm from the planet Gallifrey in the Constellation of Kasterborous. I'm 903 years old and I'm the man who is gonna save your lives and all 6 billion people on the planet below. You got a problem with that?"

- The Doctor to Rickston Slade in "Voyage of the Damned".

The Tenth Doctor was portrayed by David Tennant.

The Tenth Doctor had a manic personality with a fondness for human pop culture references. However, his more outgoing personality traits largely existed to hide leftover emotional trauma from the Time War (like his Ninth life, he was unable to retain his memory of having worked with the War and Eleventh Doctors to change the outcome). While he had a bright, playful side, darker traits occasionally emerged. He continued his previous incarnation's love for Rose Tyler, though he was unable or unwilling to express his exact feelings. He experienced other romances on occasion, including with historic figures Madame de Pompadour and Queen Elizabeth I. However, they all ended badly. He was also the first Doctor to explicitly fear and dodge regeneration, because he had grown attached to his attributes and felt like it was a form of death and loss of identity. As such, when shot by a Dalek and about to regenerate, he was able to use his cunning to abort the regeneration - though it still counted towards the limit imposed by the Time Lords - and continue on. When the time came for him to regenerate for real - this time from radiation exposure absorbed in order to save the life of his elderly companion, Wilfred - he was completely heartbroken before accepting his destiny. But not before visiting every companion he had ever known, in this life and before.

Eleventh Doctor
"I've lived a long life. And I've seen a few things. I walked away from the last great Time War. I marked the passing of the Time Lords. I saw the birth of the universe and watched as time ran out, moment by moment, until nothing remained. No time, no space. Just me! I walked in universes where the laws of physics were devised by the mind of a madman! And I watched universes freeze and creation burn! I have seen things you wouldn't believe! I have lost things you will never understand! And I know things, secrets that must never be told, knowledge that must never be spoken! Knowledge that will make parasite gods blaze!"

- The Doctor's speech in "The Rings of Akhaten."

The Eleventh Doctor is portrayed by Matt Smith.

The Eleventh Doctor was smug about his abilities and exhibited a renewed, youthful enthusiasm for adventure. He had keen observational skills, an obsession with seeming trivial. This Doctor could quickly turn frantically angry and ruthless when events demanded. He frequently referred to himself as being old, showing his age on more than a few occasions. He offered to sacrifice himself if it meant saving others on a universal scale. This Doctor's concern for his companions was greater than his predecessors; he left Amy Pond and Rory Williams back home to protect them, though eventually resumed travels with them, which ended in heartbreak. After this, the Doctor became darker and more depressed, claiming he was "retired". His attitude changed as he got to know Clara Oswald, whom he then invited to join him in the TARDIS before she fell to her death, breaking the Doctor's hearts again. He later became aware that Clara was, impossibly, scattered through time - he had previously encountered another incarnation of Clara who had died as a Dalek convert. Later, he found a third Clara, this one living in modern-day London, and the two were eventually able to learn why she was scattered through time.

A key moment in the Doctor's life occurred as the Eleventh Doctor teamed up with the Tenth and War Doctors to come up with an alternate way of ending the Time War without actually destroying Gallifrey. Although War and Ten were unable to remember this, the Eleventh Doctor found himself relieved of centuries of guilt and with a new purpose. He went on to spend many centuries (it is unknown how many) as the guardian of a town called Christmas on the planet Trenzalore. There, he aged into an ancient old man and prepared to die as the final incarnation. The Time Lords of Gallifrey, however, no longer wiped from history and on Clara's request, were able to renew his regeneration cycle, and he was able to transform once more.

Twelfth Doctor
The Twelfth Doctor is portrayed by Peter Capaldi.



He first appears in the 50th Anniversary Special "The Day of the Doctor" were he assisted his other incarnations in saving Gallifrey during the Time War. He made his first official appearance at the end of the 2013 Christmas special The Time of the Doctor, asking a stunned Clara if she happened to know how to fly the TARDIS. From what has been seen of this Doctor, he has gone back to his alien roots, obsessing over minute details and ignoring blatantly bizarre scenarios, such as a Tyrannosaurus Rex appearing in 19th century England before spontaneously combusting. He may also have the ability to communicate with animals. The Doctor doesn't seem to remember aspects of his past, though he senses some familiarity when similar events occur. Unlike other incarnations who grew into their appearances, this version of the Doctor seems fairly self-conscious, having gone from a young man to a much older one despite being renewed. He also notices that he resembles Lobus Caecilius (a character he met in The Fires of Pompeii) with an unexplained Scottish accent.

The Doctor continued his travels with Clara until her death in "Face the Raven". In the Series 9 finale "Hell Bent", the Doctor revived her and she went on her own travels in time and space with Ashildr/Lady Me.

In the 2015 Christmas special "The Husbands of River Song", the Doctor reencountered River Song, who for the majority of the episode, was unaware of his true identity until he said "Hello Sweetie" to her. After defeating the robotic body of King Hydroflax, the Doctor and River spent a 24-year long night at the Singing Trees of Darillium.

In the 2016 Christmas special "The Return of Doctor Mysterio", the Doctor, with the help of River's former assistant Nardole and a man named Grant (whom as a child, met the Doctor and accidentally ate a gem, which granted his wish to be a superhero, resulting in him becoming the Ghost), defeated brain-like aliens called The Shoal of Winter Harmony.

In Series 10, the Doctor was joined by Nardole and a new companion, a woman known as Bill Potts. At the end of the series, Bill became a Cyberman, but was restored by a oil creature known as Heather and the two travelled the universe together, whilst Nardole remained on a solar farm inside a Mondasian ship to protect it from Cybermen.

In the 2017 Christmas special "Twice Upon A Time", the Doctor will team up with his first incarnation.

Thirteenth Doctor
The Thirteenth Doctor The Thirteenth Doctor will be portrayed by Jodie Whittaker.

Unlike the previous Doctors, this incarnation is female. She will make her first appearance in the 2017 Christmas Special "Twice Upon A Time".