"Doomsday" is the thirteenth and final episode in the second series of the British science fiction television series Doctor Who. It was first broadcast on 8 July 2006 and is the conclusion of a two-part story; the first part, "Army of Ghosts", was broadcast on 1 July 2006. The two-part story features the Daleks, presumed extinct after the events of the 2005 series' finale, and the Cybermen, who appeared in "Rise of the Cybermen" and "The Age of Steel", both species having unexpectedly arrived on Earth at the conclusion of "Army of Ghosts".
The episode's plot consists mostly of the Daleks and Cybermen waging a global war, the first conflict between the two species in Doctor Who's 45-year history, with humanity caught in the crossfire. The Doctor, the Tyler family, and Mickey Smith fight for their lives trying to revert the situation, in which they are successful, but at an emotional cost to the Doctor and Rose as they are split apart.
The episode marks the final regular appearances of Billie Piper as companion Rose Tyler, Noel Clarke as Rose's ex-boyfriend and previous companion Mickey Smith, and Camille Coduri and Shaun Dingwall as Rose's parents Jackie and Pete Tyler.