The Grand Inquisitor

The Inquisitor is the currently unnamed antagonist in the upcoming television series Star Wars: Rebels. Five years before the first Star Wars movie, A New Hope, The Inquisitor was tasked with the job to seek out and assassinate any remaining Jedi in the galaxy. The one who gave him such a task is none other than the Supreme Imperial Commander Darth Vader.

History
The nameless Inquisitor, as aforementioned, serves the Galactic Empire, specifically its second most powerful entity, Darth Vader. However, the alien Pau'an assassin directly serves the Imperial subdivision The Inquistorius, one of the most high ranking divisions of the Empire that serve the two siths, Darth Vader and Emperor Palpatine. After his employment into the unit, he was tasked to execute any Jedi he discovered.