The Imperial-class Star Destroyer, often shortened to ISD and commonly referred to as the Imperial Star Destroyer or Impstar, represented a line of formidable, dagger-shaped capital ships. These vessels served within the Imperial Navy of the Galactic Empire and later, the naval branch of the First Order. Designed to supersede the Venator-class and Imperator-class Star Destroyers, the line encompassed three distinct variants: the Imperial I-class, the Imperial II-class, and the Interdictor-class.
During its zenith, the Empire maintained a fleet of 25,000 Star Destroyers, allocating twenty-four to each of the Empire's 1,024 Sector Groups. The Imperial-class became the core component of the Imperial Navy, tasked with pursuing Rebel Alliance forces, imposing blockades on rebellious planets, and functioning as mobile platforms for planetary invasions.
The Imperial-class Star Destroyer was developed as a replacement for both the Venator-class Star Destroyer and the Imperator-class Star Destroyer, both of which were utilized by the Galactic Republic during the Clone Wars.
As the initial version within the Imperial-class series, the Imperial I-class Star Destroyer was widely recognized as "the face of the Imperial Navy" and stood out as one of its most formidable warships. As one of the most prevalent vessels within the Empire's naval forces, a solitary Imperial I-class possessed the capability to subdue an entire planet or devastate it through orbital bombardment. A single battle group featuring an Imperial I could effectively isolate an entire sector.
The Imperial II-class Star Destroyer was engineered as an advancement over the original Imperial I-class. While visually quite similar to its predecessor, the Imperial II-class incorporated several significant enhancements, including a communications tower positioned between its two deflector shield generator domes instead of a tractor beam targeting array, increased firepower, a strengthened hull, and improved deflector shields.
The Interdictor-class Star Destroyer, a variant of the Imperial-class, functioned as an Interdictor. In contrast to the Imperial I-class and Imperial II-class, the Interdictor-class Star Destroyer featured a unique command hierarchy and was equipped with four spherical gravity well projectors. These projectors were powerful enough to generate an artificial gravity well, creating an interdiction field. This field could then be employed to prevent vessels from entering hyperspace, and also to forcibly remove ships from it.
The Imperial-Star Destroyer took the place of the smaller Venator-class utilized by the Galactic Republic during the Clone Wars, and generally became the Galactic Empire's preferred star cruiser. Its design was based on the Imperator-class Star Destroyer that was introduced towards the end of the Clone Wars, which saw limited action before the end of the war.
At the height of Imperial might, the Empire had over 25,000 Star Destroyers in service. The distinctive shape of the Imperial-class struck fear into the soldiers of rebellious factions, and the ship prefix ISD (short for Imperial Star Destroyer) often preceded the name of a Star Destroyer. In a report to an admiral, Senior Commander Alecia Beck made reference to the ISD Vehement.
Approximately thirty years following the Battle of Endor, the First Order, the Empire's successor, began constructing new Resurgent-class Star Destroyers to supplant the aging Imperial-class, incorporating design principles from the highly esteemed and sought-after vessel.
According to J.J. Abrams, the director of Star Wars: Episode VII The Force Awakens, his original storyboarded concept involved the film opening with New Republic vessels towing an Imperial-class Star Destroyer into the gravitational field of Jakku, with the shots intentionally mirroring the iconic opening scene of A New Hope. The wreckage, after the crash, was intended to be scavenged by Rey. Although this sequence was removed and replaced by the attack on Tuanul, animator Tim Grey recreated the initial opening sequence in a YouTube video released on February 4, 2018.
While working on the Imperial-class Star Destroyers for Rogue One: A Star Wars Story, model maker John Knoll consulted Star Wars: Incredible Cross-Sections to ensure the internal details of the ship aligned with established Star Destroyer lore.