The Curator

 was a mysterious individual who was possibly an incarnation of the Doctor. He appeared similar to the Fourth Doctor, but much older. He spoke with the Eleventh Doctor about their similarities and told him, that the name of the picture was in fact "Gallifrey falls no more," and pointed the Eleventh Doctor to start a search for Gallifrey. When the Eleventh Doctor questioned his similarity to the Fourth Doctor, the Curator told him that later on in life, he would "revisit" some of his past faces. (TV: The Day of the Doctor)