Fifth Brother was the designation used by a gray-skinned humanoid male Inquisitor of the Galactic Empire whos service began 19 years before the Battle of Yavin. On the orders of the Emperor, Darth Sidious, the Fifth Brother was dispatched by the Sith Lord Darth Vader to hunt the growing rebellion against the Empire. He later perished by the hands of former Sith Lord Darth Maul on Malachor, 2 years before the Battle of Yavin. 

The Fifth Brother was a tall, muscular humanoid male with mint eyes and gray skin. He wore the gray and black uniform of an Inquisitor, wore a metallic headpiece, and carried a double-bladed spinning lightsaber. When Ezra Bridger was captured, he attempted to execute him on the spot, only to be stopped by the Seventh Sister who derided him for his short-sightedness as the boy could be used as bait.

He should sound like his voice actor, Philip Anthony-Rodriguez.