Imperiatrix

The Imperiatrix was a title held by the first female ruler of the Time Lords, a woman known as Pandora. The Imperiatrix personal guards were known as the Imperial Guard. (BFG: Imperiatrix, Lies)

In one possible reality caused by the influx of Anti-Time, Romana II held the position of Imperiatrix of the empire of Zagreus, keeping the Dalek Emperor captive, and threatening the Dalek race with destruction. (BFA: Neverland)