Doomsday (Doctor Who) conclusion of "Army of Ghosts". The concept of the Daleks and the Cybermen both appearing on-screen was first proposed in 1967, but was vetoed by Terry Nation, the creator of the Daleks. The episode is the first conflict between the two species in "Doctor Who"s -year history, and features Billie Piper's last appearance in the lead companion role as Rose Tyler; the final regular appearance of Noel Clarke as Rose's ex-boyfriend and previous companion Mickey Smith; and the final regular appearances of Camille Coduri and Shaun Dingwall as Rose's parents, Jackie and Pete Tyler. The episode and its predecessor were
Time War (Doctor Who) their demise, the paths between worlds are now closed. The Time Lords could also prevent or repair paradoxes such as the one created by Rose in an attempt to save her father's life in a traffic accident. After the Time Lords' disappearance, such a paradox summons the Reapers, who descended to "sterilise the wound" in time by devouring everything in sight, and are only stopped by Pete Tyler killing himself. Because of the Time Lock, along with the danger of creating a paradox, the Doctor is prevented from going back in time and saving the Time Lords. The Tenth Doctor