Mathara

From Tardis Wiki, the free Doctor Who reference

Mother Mathara was a member of Faction Paradox. When Fitz Kreiner arrived on one of the Faction's warships after having been sent through the Cold, Mathara initiated him into the Faction. (PROSE: Interference - Book One and Book Two)

She later participated in the Faction Paradox invasion of Gallifrey. (PROSE: The Ancestor Cell)