Susan Foreman's mother

Susan's mother was the wife of a Cardinal on Gallifrey. On the day that she was giving birth, Lord President Rassilon sent a number of guards to terminate the pregnancy due to it violating the Legacy of Rassilon; this proclaimed the only the Loom Born could inherit the legacy of Rassilon. The First Doctor travelled to the past and saved Susan and Patience. (PROSE: Cold Fusion) Susan was apparently the last child born after the Pythia's Curse. Her mother died during childbirth, but during her youth on Gallifrey, Susan's mother would speak to her in her head. (PROSE: Lungbarrow)

Upon seeing a picture of Susan Foreman, the hermit said she took after her mother. (PROSE: The Three Paths)

She was a painter and taught Susan how to paint with watercolours before Susan left Gallifrey. (AUDIO: The Uncertain Shore)

In an account where Barbara Wright was Susan's tutor, (PROSE: Doctor Who in an Exciting Adventure with the Daleks) rather than her teacher at Coal Hill School, (TV: An Unearthly Child) Susan told Barbara that she hadn't seen her mother and father in a long time. (PROSE: Doctor Who in an Exciting Adventure with the Daleks)

Parallel universe
In a parallel universe, Susan was the daughter of the Doctor's daughter. (AUDIO: Auld Mortality)