Ahsoka pits the former Padawan of Anakin Skywalker against a new agent of the Empire, in the form of the Inquisitor called Marrok. The Inquisitors were originally introduced on Star Wars Rebels as fallen Jedi who had been recruited by the Empire and turned to the dark side, in order to serve as Jedi hunters. They were previously believed to have been either wiped out or disbanded prior to the events of the original Star Wars trilogy. Ahsoka proves that at least one survived.
Source：https://www.cbr.com/ahsoka-marrok-asajj-ventress-similarities-star-wars/
