The Grand Inquisitor

"The Jedi are dead, but there is another path. The dark side."

- The Inquisitor to Ezra Bridger The Inquisitor is the main antagonist in the Disney XD animated series, Star Wars Rebels. He serves as the Galactic Empire's inquisitor, tasked by the Dark Lord of the Sith, Darth Vader to hunt down the remaining Jedi Knights who had survived the Great Jedi Purge. He is voiced by Jason Isaacs.

Star Wars Rebels: Spark of Rebellion
In the extended cut of the television pilot, The Inquisitor appears during the opening of the film where he is being instructed by Darth Vader with a new task.

Even though the Jedi have been wiped out, the Sith have foreseen a new threat; the children of the force. Darth Vader instructs him to hunt down this new enemy and if they do not serve the Empire he should eliminate them along with any surviving Jedi who will attempt to train them.

The Inquistor appears at the end, where Agent Kallus reports his findings of the Rebels and the Jedi Kanan Jarrus for which he is pleased to hear and will hunt down Kanan and his apprentice Ezra Bridger.

Star Wars Rebels
In the episode "Rise of the Old Masters", The Rebels attempted to rescue Jedi Master Luminara Unduli, only for Kanan and Ezra to discover her deceased body encased inside a coffin. Catching them off guard, The Inquisitor tells Ezra and Kanan that Master Luminara died along with the Republic but her remains were used to lure the remaining Jedi to their end.

As the Inquisitor engaged Kanan in a lightsaber duel, he recognized his fighting skills from his teachings with Jedi Master Depa Billaba and began to mock him about how such a poor student he was when he was still an apprentice. He even gave Ezra a choice to join the Dark Side of the Force as the Jedi were no more and Kanan lacked the ways of the Jedi. Ezra refused the offer and both master and apprentice escaped from their near execution.

When the Rebels attempted to smuggle Tseebo off Lothal in "Empire Day", he led a TIE Fighter squadron to stop them from escaping. He piloted the Empire's new TIE Advanced and planted a tracking device on their ship moments before they jumped to hyperspace.

In "Gathering Forces", The Inquisitor and the Imperials followed the tracking beacon, which was planted on the haul of the Phantom to the abandoned Republic Base and where Kanan and Ezra lured them away from Tseebo, delivering him into safe hands.

The Inquisitor led a squadron of Stormtroopers down to the base and found Kanan and Ezra in connection with the Fyrnocks that inhabited the base. While the Stormtroopers took on the Fyrnocks, the Inquisitor engaged Kanan in a lightsaber duel for the second time. He quickly overpowered him and apprehended his lightsaber. Ezra tried to protect his master by standing in his way but the Inquisitor just forced him away and began to torment him with his fears of losing everyone he cared about and everything he hoped for, at the same time encouraging him to give into the Dark Side. Ezra's growing fear turned into hatred against him that he summoned an even larger Fyrnock to attack him. The Inquisitor managed to fight off the beast but Ezra and Kanan escaped him once again.

Trivia

 * The Inquisitor shares some familiar characteristics to Darth Maul from Star Wars episode I: The Phantom Menace, such as his double-bladed lightsaber. However, his is contained inside a wheel.
 * Despite his appearance and role, the Inquisitor is not a Sith. He is instead what is known as a Dark Jedi.