Sally Jacobs
From Tardis Wiki, the free Doctor Who reference
Sally was a secretary, working for the United Nations and members of staff underneath the Tower of London. Because of her blood group, A positive, she was controlled by the alien Sycorax and walked to the top of the tower to await her sudden death. After the Doctor managed to foil the Sycorax's plans, Sally, along with everyone else who was controlled, were returned to their original state. (DW: The Christmas Invasion).
She was portrayed by Anita Briem.