Lady Cassandra O'Brien.Δ17

Lady Cassandra is a recurring villainess in the TV series Doctor Who. She appears in the episodes "The End of the World" and "New Earth". She claims to be the last pure human, but due to lots of surgeries she is now only skin with a face that is stretched in a frame.

She is portrayed by Zoë Wanamaker.

History
She was born in Texas and her mother was from the Artic Desert. After she moved to England, she had married several times and extended her life through many surgeries.

Sabotage on Platform 1
At the destruction of the Earth, Cassandra was on Platform 1 and used Robot Spiders to sabotage the sun filter, take the other visitors like the Ninth Doctor, Rose Tyler, the Face of Boe and many others hostage to get ransom money for more surgery. The Doctor was able to stop her and after her assistants who had to moisturize her disappeared, her body dried and she exploded.

On New Earth
As her brain had survived, she was revived by getting a new piece of skin from the back of her old body and having her eyes being retrieved from a bin. 23 years after the Platform One incident, Cassandra resides in the basement of a hospital on New Earth ran by the Sisters of Plenitude where she had her clone servant Chip lure Rose to her and use a psychograft to transfer her mind into Rose's body. Eventually, she started to work together with the Tenth Doctor, as she wanted to survive and would switch from Rose to the Doctor and at one point, an infected patient. Eventually, Chip offers his body to her which she accepts but unfortunately due to being a clone, Chip has only a short life span so Cassandra finally accepts death, but not before the Doctor and Rose take her (still in Chip's body) back to see her younger self whose arms she dies in.