The Curator

The Curator was an elderly form of the Doctor who had retired from his adventurous ways to become "[the] humble curator" of the Under Gallery.

There was only one Curator. However, his form varied. (AUDIO: Crossed Lines) He chose to take on the appearance of former incarnations they had been, including the Fourth (TV: The Day of the Doctor), the Sixth, (AUDIO: Crossed Lines) and the Eleventh Doctors. (AUDIO: The Keys of Baker Street) He suggested to the Eleventh Doctor that his choice was to revisit "just the old favourites". (TV: The Day of the Doctor)

Each of the Curator's "aspects" had something of the personality of the original. For example, the Curator who resembled the Sixth Doctor preferred a more pragmatic, direct approach, whereas the Curator who took on the Fourth Doctor's appearance was far more cryptic, and much gentler in the presence of others.

These were evolutions of their original personalities, with wisdom from the intervening centuries and subsequent regenerations evidently helping them to become better versions of themselves. Even so, they were essentially of one mind, making decisions as one individual, even if they upheld them in different manners. (AUDIO: Crossed Lines, Lost Property, The Keys of Baker Street, et al.)

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 Eleventh Doctor's timeline became distorted, the Curator was seen as one of his future incarnations, at the end of his lifespan. (COMIC: The Then and the Now)

When Captain Lundvik threatened to shoot him, the Twelfth Doctor speculated that he would "keep on regenerating forever" if he was executed. (TV: Kill the Moon) Rassilon would later state his own uncertainty to the number of regenerations the Doctor had been granted, (TV: Hell Bent) with and  also considering their own uncertainty when debating whether to throw the Twelfth Doctor from a roof, believing they "could have been up and down the stairs all night". (TV: The Doctor Falls)

Origins
The Curator told the Eighth Doctor that he was akin to a shooting star, "shining very brightly and being very far away". (AUDIO: The Keys of Baker Street)

Semi-retirement
After deciding to retire from "getting involved", the Curator took up a position as the curator of the Under Gallery. He still had the TARDIS in his possession, which retained its police box form. (AUDIO: Lost Property)

Under "remarkable circumstances", the Curator was able to acquire Gallifrey Falls No More and brought it to the Under Gallery. (TV: The Day of the Doctor) The Curator showed his "colleague" Henry Black the Gallifrey Falls No More painting, and even updated him on the extended title of the work, Gallifrey Falls No More (Until the Next Time). (PROSE: Dr Black)

At some point the Curator rang Anke Von Grisel, curator of the Verbier Museum of the Impossible, to apologise for his previous arrogance, admitting that the artefacts that she kept only existed because of the Tenth Doctor's mistakes during the Kotturuh crisis. He warned her that he worried that, in causing those things to exist, his tenth incarnation may have opened a door to "let something in", (PROSE: Canaries) allowing Different and Same to escape the Last Great Time War through paradox energy. (PROSE: The Paradox Moon, Canaries)

Reunions
Many years after the Eighth Doctor had regenerated on Karn, in circumstances "too scandalous to relate" to others, the Curator asked Ohila what had been in his regeneration potion that supposedly contained the Elixir of Life. He and Ohila were good friends by this point, and she told him she had actually given him dry ice and lemonade and went on to explain that the dark nature of the Doctor had always been inside of him and she just needed him to believe it had come from somewhere else while he was the War Doctor.

The Curator was often visited by Clara Oswald, although he pretended not to remember her.

The Curator made many visits to Alistair Gordon Lethbridge-Stewart and they got up to a lot of "mischief" and laughed with each other until he died, with the Curator often hiding under Alistair's bed when Kate Stewart came to visit so her father could pretend she was his only visitor. During one of his visits, the Curator asked him what the most important quality in a UNIT commander was, and he responded with the answer of "good handwriting". One activity they did was play Risk together, with Alistair always being the Daleks, which the Curator found "a bit unfair".

On another of his visits to see Alistair, he told him he was planning to write a book about the last day of the Last Great Time War called the Doctor Papers. Alistair told him that information within it was classified material to which the Curator responded he had a plan to mark the book as fiction. The Curator had the Doctor Papers published on psychic paper in 2003. (PROSE: The Day of the Doctor)

The day of the Doctor
At around the time the time fissure appeared in the Under Gallery in 2013, the Curator was in the middle of moving some of the more dangerous artefacts in the Under Gallery to the Black Archive marking the empty display cases and stands with a "B".

For the Doctor Papers, the Curator compiled them together in order to make comments about them. The sections where the Curator talked to the reader, however, were written live and sent ten years into the past because he got "sloppy about the deadline". Towards the end of the book, the Curator got his webcam working, meaning it would automatically translate what was going on into prose. As a treat, he set off to find his past incarnations and discover the identity of a mysterious stranger who met with him, possibly from the Doctor's past or future. (PROSE: The Day of the Doctor)

When his war, tenth and eleventh incarnations rendezvoused at the National Gallery after the final battle of the Last Great Time War, the Curator approached Clara Oswald, telling her he was looking for the Doctor. (TV: The Day of the Doctor) Another account suggested he accidentally alerted the Eleventh Doctor to his presence by speaking to himself around the corner at which point he decided to get involved in the narrative, even though it was strictly against rules. (PROSE: The Day of the Doctor) When the Eleventh Doctor was alone, the Curator made his presence known when the Doctor noted how he could retire and be a curator, with the Curator exclaiming that he "really [thought] [the Doctor] might." Stunned by how familiar the Curator was, the Doctor noted that he "never [forgot] a face", the Curator merely noted that the Doctor would revisit a few in years to come but just the "old favourites".

He told the Doctor that the name of the painting was neither No More nor Gallifrey Falls, but in fact one title Gallifrey Falls No More. Despite proclaiming to be a "humble curator [who] wouldn't really know", he told the Doctor that Gallifrey was lost, and pointed him in the direction to search for it, telling him he had "a lot to do" and congratulating him. When the Doctor tried to pry into his meaning, the Curator retaliated by pointing out it was the Doctor's choice. He was then about to tell the Doctor what he would do if he was him, but then teasingly said that "perhaps [he] was [him]," or that maybe the Doctor had been him, before deciding that it "[didn't] matter either way" and left (TV: The Day of the Doctor) to have tea with Ohila and Elizabeth I, deeming "the day of the Doctor" to have finally ended. (PROSE: The Day of the Doctor)

Curating Baker Street
The Curator personally chose the tenants of 107 Baker Street, meeting Tania Bell whilst in the form of an elder Eleventh Doctor. (AUDIO: The Keys of Baker Street)

In the alternate 2020 created by the crash landing of the Eighth Doctor's TARDIS, (AUDIO: Crossed Lines) the Curator was reunited with Liv Chenka and Helen Sinclair outside of the Eighth Doctor's damaged TARDIS, although he kept his identity secret. He visited Jim to ask what he had given to the Eighth Doctor, feeling that time would soon be other than it should. He later told Ron Winters to send Midge to the Under Gallery and then encountered Liv and Helen again in a cafe, paying their tab. After giving Robin Bright-Thompson money for a hot chocolate, he visited Midge to jog his memory about the Pandora Bolt. The Curator allowed Helen to follow him and told her to look after the Doctor. (AUDIO: Lost Property)

The Curator met Helen again in Trafalgar Square, suggesting she look closer to home regarding the impact of the recent paradox. He later encountered Gemma Houlbrooke on a bench in Camden. (AUDIO: The Long Way Round)

After the Eighth Doctor began meddling in the recent past, Liv took Tania to the Curator as she was struggling with her changing memories. Currently in his more proactive form of an elder Sixth Doctor, the Curator helped stabilise Tania and explained to Liv the damaged state of time. The Void began encroaching on them as reality destabilised, so the Curator took them to the train in past where the Doctor was altering time to pass on the information. He held back the Void to enable them to reach the Doctor. (AUDIO: Crossed Lines)

After another attempt by the Doctor to correct history led to the alternate timeline dissolving entirely, the Curator made arrangements for 107 to survive, filled with time windows of its recent past, and brought Robin Bright-Thompson there from the distant future. After experiencing the hints the Curator had left, the Doctor, Liv, Helen, Andy Davidson and Robin found him in the house's attic with Tania. The Curator advised the Doctor and helped his companions reach another alternate timeline, leaving the Doctor and Robin together in remains of 107's attic in the Void to give them time. With his cryptic guidance, Liv and Helen devised a way to use their keys to retrieve the Doctor and Robin from the Void, resetting the timeline in doing so. With the true 2020 restored, the Curator met with Mr Bird before he faded away due to time's correction. (AUDIO: The Keys of Baker Street)

Appearance
In one of his forms, (AUDIO: Crossed Lines) the Curator had the appearance of an elderly Fourth Doctor, the Curator's face was wrinkled with baggy cheeks, a hooked nose and a pronounced throat. He had light blue eyes and big ears with dangling ear lobes. Though he was balding, his hair was completely white and he lacked eyebrows. (TV: The Day of the Doctor)

In another form, the Curator resembled an older Sixth Doctor, balding. (AUDIO: Crossed Lines)

Tania Bell met the Curator when she moved into 107 Baker Street. In this instance, he had taken the form of an elderly Eleventh Doctor, who was "all bow ties and elbows. (AUDIO: The Keys of Baker Street)

Clothing
In his Fourth Doctor appearance, the Curator wore a blazer of olive green herringbone-tweed, a beige and maroon tattersall shirt, mahogany brown trousers and caramel brown slip-on shoes with ivory socks. In his blazer breast pocket, he kept a crimson handkerchief. He also walked with a cane and wore a navy blue ascot tie under his shirt. (TV: The Day of the Doctor) He also once wore a burgundy ascot tie, a cream shirt, a black belt with a buckle and a sportjacket of bracken green moleskin. (COMIC: The Then and the Now)

In his Sixth Doctor appearance, he wore a violet moleskin frock coat with a silver cat brooch, a mustard yellow corduroy waistcoat, an alabaster shirt, and a turquoise bow tie. (AUDIO: Crossed Lines)

As previous incarnations of the Doctor had done, the Curator owned a pair of "brainy" glasses that he didn't actually need, but would occasionally put on to make himself look clever. (PROSE: The Day of the Doctor)

Identity
An early draft of The Day of the Doctor has the Moment serve in the role of the Curator. Moffat later reflected that is was possible to interpret that the character was the Moment finding a form to speak to the Doctor through, however his intentions of the scene was simply that the Curator was a future incarnation of the Doctor, who had settled down and picked a new face every day to revisit.

This is never concretely stated in either the script or dialogue of Day of the Doctor, and the audience was essentially left to believe that this was either the Doctor or a person who looked like the Doctor and enjoyed insinuating that he might be him. Baker played the part in a heavily meta way, seemingly stopping briefly to congratulate Matt Smith instead of the Eleventh Doctor, and then turning the final line ("who knows?") into a pun, by tapping his nose (thus, "Who nose"). Like all the other Doctors, Baker is listed only as "The Doctor" in the credits sequence.

The first narrative story to unambiguously state that the Curator was a future Doctor was COMIC: The Then and the Now, which illustrated the timelines of the various characters being briefly refracted around them. The Eleventh Doctor was seen with the First Doctor to his back and the Curator to his front, revealing his past and future.

Since then, it has become standard for numerous pieces of media to feature the Curator as an unambiguous future incarnation of the Doctor, including the novelisation for Day of the Doctor and Big Finish's Stranded series, which expanded on Steven Moffat's original concept.

Memory
In DWM 487, showrunner Steven Moffat suggested that, just as the war and tenth incarnations retain no memory of the events of The Day of the Doctor, the Eleventh Doctor would not remember the specifics of his conversation with the Curator but will leave the Under Gallery "with the strange, groundless conviction that Gallifrey is still out there". This is reflected in The Time of the Doctor, where the Eleventh Doctor voices his uncertainty regarding whether Gallifrey was actually saved (and also indicates that he has no future incarnations, an important plot point of the episode).

Other matters

 * Curiously, the incarnation of the Doctor from The Nest Cottage Chronicles, an incarnation that was "transcendent" of continuity, was also portrayed by Tom Baker.
 * Baker later reprised that role in Baker's End, albeit with the Doctor being changed to be more of a parody of Tom Baker with some Doctor-ish qualities. What makes the connection to the Curator notable, however, is that Paul Magrs, author of The Nest Cottage Chronicles and Baker's End, once proposed the theory that the Nest Cottage Doctor was actually the Curator, and even more notably, is that in Baker's End, "Tom Baker" died and came back to life as Colin Baker, in a process similar to regeneration, and the Curator coincidentally has been portrayed by Tom Baker and Colin Baker.
 * Tom Baker previously played several other nameless characters suggested to be future incarnations of the Doctor.
 * In the 1992 release of Shada Baker played the narrator for the unfinished links of the story. He described this as a "cancelled" adventure of his, and he mentioned that he had once defeated the Cybermen, Daleks, and Davros. He wore a pin stripe suit, a blue shirt, and a floral tie.
 * In 1997 Baker played the Doctor in a series of superannuation advertisements in New Zealand.
 * In an Introduction to the Night for the 1999 Doctor Who Night Baker's future version of the Doctor referred to the Doctor in the third person but walked through in the Doctor's TARDIS and mentioned that he was "called Paul McGann in this one" when introducing TV: Doctor Who. He encountered multiple Daleks in the TARDIS before he introduced a "night of pure entertainment". This character was forgetful and consequently found himself laughing at most situations; he wore a black suit jacket, an open-neck shirt, and an ivory cravat.
 * Despite Big Finish's license being expanded to include the new series of Doctor Who, the BBC specifically instructed them not to use the Curator character in their audio dramas, (VOR 88) though after discussions with Steven Moffat, this decision was later overturned, allowing the Curator to be included extensively in the Stranded series.