The Tector-class represented a specific type of Star Destroyer that served within the Imperial Navy throughout the Galactic Civil War. A key difference from other Star Destroyer types was its absence of a bottom-side hangar bay. In the year 4 ABY, a vessel of the Tector-class, identified as the Harbinger, participated as part of the Galactic Empire's fleet in the defense of the second Death Star above the Forest Moon of Endor.
Following the Rebel Alliance's forces initiating an assault against the seemingly unfinished battle station, the Imperial fleet, under the scheme of Emperor Palpatine, trapped them. As the Alliance started attacking the Imperial ships, the rebel freighter Millennium Falcon traversed the hull of the Harbinger. Rebel ships then destroyed the Star Destroyer as they advanced, and shortly after, the Death Star was also destroyed, taking with it a significant number of Imperial forces.
The Tector-class initially made an appearance as a ship in the background, lacking a hangar, in the 1983 original trilogy movie, Star Wars: Episode VI Return of the Jedi. While the film did not name it, it received a class designation within the new Star Wars canon through "The Levers of Power," a short story authored by Jason Fry and featured in the 2015 collection The Rise of the Empire.
Within the Star Wars Legends continuity, the Tector-class Star Destroyer received its first mention in Curtis Saxton's 2005 reference work, Star Wars: Revenge of the Sith Incredible Cross-Sections. Leland Chee later confirmed on the StarWars.com Message Boards that this class was the Star Destroyer without a hangar observed in Return of the Jedi. Chee's statement expanded upon the novelization, Star Wars: Return of the Jedi: The Illustrated Edition, which featured a passage, accompanied by concept art from Return of the Jedi, validating that the portion of the Tector seen in the film was its ventral hull. In Latin, the term "tēctor" translates to "plasterer."