The Imperial Security Bureau (ISB), also referred to as the Imperial Security Office or the Imperial Secret Service, was a law enforcement and intelligence agency of the Galactic Empire that was charged with matters of internal state security and ensuring the loyalty of citizens to the Empire. Aside from that, it happened to be one of the many umbrella organizations under the greater Commission for the Preservation of the New Order (COMPNOR), and was larger than its sister agency Imperial Intelligence. It was led by ISB high command.

Imperial Intelligence, also known as Military Intelligence (MI) or Imperial Military Intelligence, was an espionage organization of the Galactic Empire that provided services on their own accord and also fed resources to the other Imperial Military branches, the Joint Chiefs, and Emperor Sheev Palpatine. Imperial Intelligence was organized out of five Galactic Republic intelligence agencies, one of which was Republic Intelligence. The agency orchestrated the Senatorial arrests and played a large role in the intelligence gathering during the Berch Teller campaign. It had oversight of the operations of the Naval Intelligence Agency, which was briefly made a separate organization before being folded back under Imperial Intelligence. MI also had weapons development oversight of Department of Advanced Weapons Research. Director Orson Callan Krennic, the leader of the secretive department, was a member of Imperial Intelligence. Whilst a member of MI, Krennic used every tool at his disposal to find Galen Walton Erso to bring him back into Imperial service.

In 4 BBY, Tseebo, an agent of the MI affiliated Imperial Information Office, fled with confidential data. The Rodian escaped from Lothal into hiding with the help of the Spectres rebel cell. Later, IIO Controller LT-319 and the personnel of his IGV-55 surveillance vessel embarked on a mission to hijack the Spectres’ C1-series astromech droid Chopper and use him to obtain intelligence on the Phoenix Cell‘s hidden base. However, they were defeated by Chopper’s rebel allies and the former Imperial RA-7 protocol droid AP-5. In roughly 1 BBY, a squad of death troopers were tasked with guarding a kyber crystal being transported aboard a freighter to the Tonnis sector for Project Stardust. Death troopers led by Director Krennic executed the scientists of the kyber crystal research team to punish their team leader, Galen Erso, for conspiring with enemies of the Galactic Empire. Furthermore, death troopers participated in the battle of Scarif and the battle for Tatooine during the Galactic Civil War. In around 1 ABY, Imperial Intelligence had leads on a Rebel Alliance outpost, which eventually resulted in its destruction by the members of Task Force 99.