The Harpax was an Immobilizer 418 cruiser that saw action during the Galactic Civil War within the ranks of the Imperial Navy. It participated in the mission to eliminate the forces previously led by the defector Admiral Harkov. While Harkov's Victory-class Star Destroyer, the Protector, was replenishing its supplies, the Harpax ambushed it. Utilizing its gravity well projectors, the Harpax successfully ensnared the Protector, preventing its escape into hyperspace. However, the Protector managed to summon assistance. The Rebel MC40a light cruiser Warhawk and Harkov's frigate Akaga arrived to support the besieged vessel. The Harpax found itself facing a superior number of enemy ships and was outmaneuvered.
The interdictor cruiser then requested reinforcements, which materialized in the form of the Star Destroyer Garrett with Darth Vader aboard. Although all three Alliance warships were destroyed, the Harpax had suffered irreparable damage and was subsequently obliterated.
Despite the possibility of saving the Harpax in Star Wars: TIE Fighter, its destruction is validated through Maarek Stele's mission log in TIE Fighter: The Official Strategy Guide. A typographical error occurs in the video game, and three times on page XVII of the TIE Fighter Collector's CD-ROM: The Official Strategy Guide, where the cruiser's name is rendered as "Harpox," although the correct spelling is used elsewhere.