Barack Obama

Barack Obama was the President of the United States in the early part of the 21st century, and was resident in the White House at the time became every human on Earth. During a globally-publicised press conference in which the president was to announce his plan to reverse an economic downturn, the Master used the Immortality Gate to turn Obama, and everyone else on the planet, into a member of the so-called "Master Race". After the substitution had taken place, the Master indicated that he'd somehow "deleted" Obama's economic plans from the president's brain. It was unclear whether the American retained his economic insight after Rassilon's gauntlet eliminated the "Master Race". (TV: The End of Time)

Behind the scenes

 * Barack Obama was played in The End of Time by an uncredited stand-in whose face was obscured from camera view. The actor's back was to the camera and a sound clip of the real Obama's voice was heard as the character began his speech. Brief footage of the real Obama is also shown. In the Doctor Who Confidential episode Lords and Masters, the actor's face was briefly seen during a break after shaking his head around for the transformation of Obama into the Master.
 * Barack Obama was the first sitting real-life American president to be depicted in a televised Doctor Who story. Obama's relationship to his fictional predecessor, President Arthur Winters is considerably unclear. It's not known whether Winters, who was killed by  in The Sound of Drums, was Obama's immediate predecessor — in which case Obama would have been Winters' Vice President, or whether he simply won the 2008 general election, and took over from an interim, "caretaker" president.  Both eventualities are possible, given the vagueness of the scripts involved.
 * In the episode Dalek, Diana Goddard mentions she thinks the next president will be democrat. Barack Obama, who was a democrat, received a second term. This therefore proves her prediction correct.