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, having been kicked out of the Bureau for wanting to have a gay marriage. He served as the Doctor's fourth companion (as he already had Rory, River and Amy) during his investigation of the Silence. He quickly came to respect the Doctor during their quest to defeat the Silence, hoping to have another adventure with him in the future.

The Silence
Canton was an FBI agent who was forced to quit the Bureau. Six weeks after his resignation, on 8 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 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 shot 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 understanding that Canton intended to marry a black man prompted Nixon to reconsider the idea. (DW: Day of the Moon)

Remeeting
In 2011, Canton was invited by a future version of the Doctor to the place where the Doctor would be shot and killed. There he met River, Amy and Rory again, told them that it was definitely the Doctor and that he was really dead. He left them gasoline to burn the Doctor's corpse. The Doctor had secretly used a Teselecta duplicate to fake his own death, and the gasoline barely singed it. (DW: The Impossible Astronaut, The Wedding of River Song) Canton also told them that he wouldn't see them again, but they would see him; 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, and suggested his father for the role. Both actors appear in the Star Trek franchise as well as in the Nintendo Wii FPS The Conduit.
 * Mark Sheppard has stated he would like to return as Canton and added he sees Canton "more like the Brigadier than Amy or Rory"