Peter Capaldi (born 14 April 1958), is a Scottish actor and Academy Award-winning director. He has played three roles in the Doctor Who franchise, most notably that of the Twelfth Doctor. He first played the Doctor in a brief cameo in The Day of the Doctor, broadcast on 23 November 2013, and succeeded Matt Smith in the role officially in the following story, The Time of the Doctor, first broadcast on 25 December 2013.
Matthew Robert Smith (born 28 October 1982), more commonly known as simply Matt Smith, is an English actor. He portrayed the Eleventh Doctor on Doctor Who and in the 2010 two-part storyline Death of the Doctor for the Doctor Who spin-off series The Sarah Jane Adventures.
David Tennant (born David John McDonald on 18 April 1971), is a Scottish actor and voice actor who portrayed the Tenth Doctor from 2005-2010, taking over the role of the Doctor from Christopher Eccleston at the conclusion of The Parting of the Ways. He made his final regular appearance in the role in The End of Time, a special two-part story that concluded on New Year's Day 2010, after which Matt Smith took over the role of the Doctor.
Christopher Eccleston (born 16 February 1964 in Salford, Greater Manchester) is an English actor. He portrayed the ninth incarnation of the Doctor, from Rose to The Parting of the Ways.
John Hurt's was not a conventional incarnation of the Doctor; although Hurt portrayed the ninth in chronological order, he is officially known as the War Doctor. He is also the only official incarnation of the Doctor whose tenure was entirely within another actor's tenure, his entire stay in the role being within Matt Smith's run as the lead.