Cassandra (Doctor Who)

Lady Cassandra O'Brien.Δ17 ("dot Delta Seventeen") is a fictional character in the British science fiction television series Doctor Who. Portrayed by actress Zoë Wanamaker, Cassandra is a human who has undergone so many plastic surgeries in an attempt to become more beautiful that she is now just a stretched piece of skin on a frame. Cassandra first appears in the 2005 episode "The End of the World", where she attempts to sabotage a viewing party for the destruction of the planet Earth in order to obtain more money to fund further surgeries. Cassandra is seemingly destroyed, but later re-appears in the 2006 episode "New Earth", where she possesses the body of the Doctor's companion Rose Tyler. Cassandra is eventually forced out of Rose's body into another body, which begins to die. The Doctor takes Cassandra back in time to see her past self, and she dies in her past self's arms.

Cassandra was created by then-showrunner Russell T Davies, who was inspired to create Cassandra by drastic beauty treatments that female celebrities had undergone. Cassandra was an entirely CGI-animated creation, which proved to be troublesome for the production team. The popularity of the setting of "The End of the World", as well as Davies's personal fondness for the character, resulted in her re-appearance in "New Earth". To prevent issues with the CGI animation used in her prior appearance, Cassandra was made to possess others throughout the episode, minimising the time her CGI appearance was on-screen.

Cassandra has received a largely positive response since her debut. She has been analysed for the real-world commentary and symbolism present in her character, as well as for the series' depiction of her as "inhuman" despite her human origins.