Bill Potts's mother

Bill Potts' birth mother died soon after childbirth.

History
Bill's mother at one point met the Twelfth Doctor, who would take many pictures of her during their brief time together. These would eventually be passed on to Bill.

Bill's mother died when she was just a baby. (TV: The Pilot)

Legacy
Bill would often think of her mother, despite having never truly known her. She was often told that she looked like her, and she would imagine her mother telling her wise phrases despite her lack of presence.

Bill had no pictures of her mother, and upon telling this to the Twelfth Doctor after he had failed to deliver her a Christmas present, he traveled back in time to correct this. (TV: The Pilot)