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 his homosexuality and intention to marry a man. Six weeks afterwards, on 8th April 1969, he met with President Nixon at the White House to investigate mysterious telephone calls he was receiving. There he met the Eleventh Doctor and allowed him to help in the investigation. He 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)

In order to prevent the Silence from learning about their discovery of their presence, Canton pretended to lead the hunt for Amy, Rory and River after the Silence arranged for them to be declared fugitives while the Doctor was held prisoner in Area 51. After the Doctor was sealed in a dwarf star matter 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 subsequently arranging for that message to be broadcast during Neil Armstrong's moon landing; the Silence essentially ordered Earth 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's fiance was a black man  prompted Nixon to reconsider (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, and left them gasoline with which to burn the Doctor's body. After his departure, the trio met a past version of the Doctor and searched for Canton in an attempt to change what had transpired. (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.