Peter Capaldi
Peter Capaldi (born 1958, Glasgow) played the Twelfth Doctor from his brief and wordless introduction in The Day of the Doctor. He is the only person to win an Academy Award prior to taking on the role of the Doctor, although the Oscar® was not for acting. Instead, he won in the Live Action Short Film category for Franz Kafka's It's a Wonderful Life starring Richard E. Grant. Indeed, Capaldi is the only actor to play the Doctor to have significant above the line credits prior to taking on the job.
He also came to the role with impressive DWU acting credits. Before becoming the Doctor, he had been Caecilius, a principal guest star in the Doctor Who story The Fires of Pompeii and John Frobisher in Torchwood: Children of Earth.
During the Jon Pertwee years of Doctor Who, Capaldi sent scripts to the production office. Barry Letts began a correspondence with Capaldi, which eventually resulted in an invitation for the youngster to visit BBC Television Centre. Capaldi met Letts, Terrance Dicks and Pertwee. He later cited the incident as formative to his career as a professional actor, writer and director. (BBC DVD: The Monster of Peladon)
Capaldi was announced as the Twelfth Doctor in a live broadcast simulcast worldwide on 4 August 2013. His debut appearance during the climax of TV: The Day of the Doctor was kept a surprise from viewers as the BBC had indicated he would debut at Christmas. His initial appearance, lasting only a couple of seconds, reveals little other than his hand pulling a lever in his TARDIS and an extreme close-up on his eyes.