The Imperial siege balloon represented a type of aerostat employed by the Galactic Empire during the period of the Galactic Civil War.
These Imperial siege balloons were visually characterized by a canopy colored in shades of brown and red. Propulsion was achieved through the use of three gas jets. Beneath the canopy, a platform was suspended via a network of wires. Situated around the platform's edge were six laser cannons. These gas jets presented a vulnerability; their destruction would cause the balloon to plummet, and sever the wire connections between the canopy and the platform. The spacing of the wires allowed an RZ-1 A-wing interceptor to navigate through them. They shared design elements with the Floating health spas.
During the Rebel's Raid on Bespin, Imperial siege balloons saw action. The Imperial forces directed the laser cannons of these balloons towards the gas platforms, opting to destroy them rather than allow the Rebels to gain control. However, the Rebels capitalized on the vulnerability of the exposed gas jets, causing the balloons to crash onto the surface of Bespin.
The initial appearance of Imperial siege balloons occurred within the Star Wars: Rogue Squadron video game series. They were first featured in Star Wars: Rogue Squadron II: Rogue Leader, and subsequently reappeared in the cooperative gameplay mode of Star Wars: Rogue Squadron III: Rebel Strike.