Canton Everett Delaware III

Canton Everett Delaware III was an ex-FBI agent who accompanied the Doctor during the latter's visit to America in 1969.

Biography
Canton was an FBI agent who was forced to quit the bureau due to his homosexuality and intention to marry a black man. Six weeks after his resignation, on 8th April 1969, he met with President Nixon at the White House to investigate mysterious telephone calls Nixon was receiving. There Canton met the Eleventh Doctor and allowed him to help in the investigation. Canton travelled with the Doctor to Florida in search of the little girl who had been calling. Rory Williams explained to Canton how the TARDIS travelled through both time and space and was bigger on the inside. (DW: The Impossible Astronaut)

The Silence arranged for the companions to be declared fugitives and the Doctor held prisoner in Area 51. Canton pretended to lead the hunt for Amy, Rory and River in order to prevent the Silence from realising their presence was known. After the Doctor was sealed in a dwarf star alloy prison that prevented anything getting out, he and Canton revived the captured Amy and Rory, recovered River Song, and departed in the TARDIS- which had been hidden in its invisible form behind the Doctor as the prison was constructed- to track down the little girl. After Canton managed to injure one of the Silence, he used Amy's video phone to record the Silence saying "You should kill us all on sight!". The Doctor arranged for that message to be broadcast during Neil Armstrong's moon landing; the Silence essentially ordered every human who ever saw the footage to murder them and forget they'd done it. As the Doctor departed, he suggested that Nixon allow Canton to get married, but the discovery that Canton intended to marry a black man prompted Nixon to reconsider the idea. (DW: Day of the Moon).

In 2011, Canton was invited by a future version of the Doctor to the place where the Doctor would be shot and killed by the astronaut. There he met River, Amy and Rory again, told them that it was definitely the Doctor, that he was really dead, and left them gasoline with which to burn the Doctor's body.

Canton told them that he wouldn't see them again, but they would see him, because, for them, this was before they had met his younger self. (DW: The Impossible Astronaut)

Behind the Scenes
Mark Sheppard, who played Canton in 1969 is the real-life son of William Morgan Sheppard, who played him in 2011.