Also known as the Master, she was the Doctor's childhood friend (they were both boys back then). They dreamed of traveling the universe together, but the Master was quite insane. As Missy, she was kept prisoner by the Doctor (in lieu of killing her for her crimes). In the end, she was killed by an older version of herself, whom she also killed. Don't try to think about it.
This page was last edited on July 26th, 2019.