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
Companion (Doctor Who) "what constitutes a Doctor Who companion is no longer clear". During the Doctor's latest incarnations, his primary companions, such as Rose Tyler and Martha Jones, have fulfilled a distinct dramatic role, more significant than other, less-prominent TARDIS travellers such as Adam, Jack, and Mickey. The British press referred to Martha as the "first ethnic minority companion in the 43-year television history of "Doctor Who"" and the "first black assistant", despite the presence of Mickey Smith in the previous season—including several episodes in which he travelled in the TARDIS with the Doctor. Similarly, some characters who appear to qualify as companions