Imperial Sentry Droids were utilized by the Galactic Empire aboard its Imperial Cargo Ships. Should one of the activated sentry droids fall under attack, the remaining deactivated droids would power on.
It is unknown when the Imperial Sentry Droids went into service, though AP-5 was aware of their existence prior to joining the Rebellion. The Ghost Crew, Hondo Ohnaka, Azmorigan, and Melch later encountered several Sentry Droids aboard a cargo ship abandoned over planet Wynkahthu. One droid took Azmorigan and Zeb captive, and its compatriots were activated when Azmorigan foolishly attacked it with a blaster. The Sentry Droids attempted to eliminate the thieves as they were fleeing the ship, but failed and were lost with the vessel when it fell into Wynkahthu's storms.
Grand Admiral Thrawn was later shown to maintain Sentry Droids as sparring opponents, along with one that stood inert in the corridor leading to his office aboard the Chimaera. Kallus later reprogrammed the droids so that they would no longer accept Thrawn's override code and had them attack Thrawn, allowing Ezra Bridger to escape Thrawn's office after infiltrating it. However, Thrawn was able to disable both Sentry Droids without sustaining any serious injuries.
- The Imperial Sentry Droids were inspired by the Dark Troopers seen in the Star Wars Legends video game Star Wars: Dark Forces.
- The override code Thrawn uses for his Imperial sentries was initially interpreted as either "Rook," a reference to the chess piece and thus Thrawn's tactical knowledge, or "Rukh", a reference to Thrawn's Noghri bodyguard from the Legends continuity. Rukh was later added to the show in season 4.