The Curator

The Curator was an elderly incarnation of the Doctor, whom had retired from his adventurous ways to become "a humble curator." He curated the Under-Gallery, where he watched over the painting Gallifrey Falls No More, after acquiring it under "remarkable circumstances."

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

Interaction with his eleventh incarnation
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.

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 [though] [the Doctor] might." After the Doctor noted that he could remember his face, the Curator merely noted that the Doctor would revisit a few old favourite faces in years to come.

He spoke with the Doctor and told him that the name of the painting was neither No More nor Gallifrey Falls, but in fact one title; Gallifrey Falls No More. and pointed the Doctor in the direction of a search for Gallifrey, telling him he had "a lot to do". He also congratulated the Doctor on his success. (TV: The Day of the Doctor)

Appearance
The Curator had the appearance of an elderly version of the Fourth Doctor. (TV: The Day of the Doctor)

Clothing
He walked with a cane and wore a cravat under his shirt. (TV: The Day of the Doctor)

Behind the scenes

 * The script never directly states that this character is the Doctor, but hints that he may be a future incarnation who has adopted the same form as his fourth, or is in fact said previous incarnation. COMIC: The Then and the Now later depitcs him as a future incarnation of the Doctor when the Doctor's timeline becomes distorted.
 * Tom Baker is not separately credited for this performance, receiving only a credit for playing "the Doctor" (as did all the other past Doctor actors, who appeared in the episode through the use of archive footage).
 * Early in the episode Queen Elizabeth I's letter appoints the Doctor as "curator of the Under-Gallery."
 * The Curator states that he acquired the painting "under remarkable circumstances", and yet Queen Elizabeth I had instructions regarding it.
 * Tom Baker played a similar nameless character, with the appearance of an older Fourth Doctor, in a series of idents for the 1999 Doctor Who Night. Like the Curator, he is never stated to be the Doctor and refers to him in the third-person, but is shown in the TARDIS and says that he's "called Paul McGann in this one" when introducing the TV movie. He also similarly appeared as the narrator for the unfinished links of Shada, speaking as the Doctor in an exhibition of the monsters he fought while also acknowledging the actors and Shada's cancellation.

Conservateur (The Day of the Doctor) Curador (The Day of the Doctor)