Ada

Ada Gillyflower was a human living in Victorian Yorkshire. She was blind and had scars on her face from her mother, Winifred's, experiments with red leech poison to create an antidote from the toxins.

Ada attended her mother's sermons and was used as an example of human ignorance. Her mother claimed that her blindness was caused by her father during a drunken rage.

Ada was told to dump the Eleventh Doctor in the river after becoming a reject of Mr Sweet's poison, but the Doctor survived. She locked him away and referred to him affectionately as "her monster".

When the Doctor was restored, he told Ada the truth about her mother's actions towards her, and she turned against her mother, even beating her mother with her stick after her mother admitted the truth about her experiments. After Clara destroyed the rocket launcher, Ada's mother held a gun to Ada's head to hold the Doctor back. When her mother was killed by Strax, she destroyed Mr Sweet. After these fateful events, the Doctor asked her what she would do with her life, to which she replied, "There are many things a bright young woman can do".

Biography from the TARDIS Data Core article, licensed under CC-BY-SA