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
The Doctor (Doctor Who) future?" to which he replies, "It does start to happen, yeah." The series has played with the idea of a romantic relationship between the Ninth Doctor and Rose Tyler, with many characters assuming they were a couple. Rose's boyfriend Mickey Smith clearly views the Doctor as a romantic rival for whom Rose has left him. Each shows flashes of jealousy when the other flirts with other characters. In "The Parting of the Ways" (2005), the Doctor's male companion Jack Harkness kisses both the Doctor and Rose in what he believes is a last goodbye. In the same episode, the Doctor