The Empire is the main faction in Star Wars, with the oppressive nature of the dictatorial government being the focus of many of the stories set immediately after the fall of the Republic and long after the Empire's fall. As Star Wars storytelling has gone on, it's fleshed out how the Empire has managed to keep a grip on the galaxy. Two key organizations key to this are the Imperial Security Bureau (ISB), which acts as secret police, and the Inquisitorius, Dark side Force-users under the command of Darth Vader.
Source：https://www.cbr.com/star-wars-fragile-imperial-security-bureau-inquisitors/
