Luass

Shssur Luass was the sister of Artix, wife of High Lord Uzoxx and the mother of Izaxyrl. She plotted with her brother to kidnap her son during his Ascendance Rite, making him ineligible to inherit the throne and allowing Artix to succeed her husband. She further planned to have Artix killed so she would get the throne for herself. She later killed her servant Tuross to frame the Eighth Doctor for his murder. After she killed Artix for exposing her treachery, Uzoxx shot and killed her. (RT: Descendance, Ascendance)