Doctor Who (series 4) Astrid Peth, who died during the events of the episode. The companions in the regular series had all been in the lead companion role previously: the primary role of Donna Noble, who was introduced in "The Runaway Bride", was played by Catherine Tate for all thirteen episodes. Her return was announced by the BBC on 3 July 2007. Freema Agyeman, who portrayed the Doctor's companion Martha Jones in series three, returned for "The Sontaran Stratagem", "The Poison Sky", "The Doctor's Daughter", "The Stolen Earth" and "Journey's End". Billie Piper, who played Rose Tyler from the first episode of the new
Rose (Doctor Who episode) (Christopher Eccleston) plot to prevent an invasion of the Earth by the Nestene Consciousness (voice of Nicholas Briggs) and the Autons after the Doctor destroys Rose's workplace. The episode marked Eccleston's first appearance as the Doctor, succeeding several other actors who played the role, and Piper's debut as the Doctor's travelling companion Rose. Being the first episode of the revived series, several recurring characters were introduced: Camille Coduri as Jackie Tyler, and Noel Clarke as Mickey Smith. Viewers did not see the Doctor character regenerate from a previous incarnation, regeneration being a plot device in which the character of the