A Star Destroyer was a dagger-shaped type of capital ship that were used by the Galactic Republic, the Galactic Empire, the First Order, and the Sith Eternal. Notable examples of Star Destroyers include the Imperial-class Star Destroyer and its predecessor the Venator-class Star Destroyer.
According to Everi Chalis, Star Destroyers were the most resource-intensive ships the galaxy had ever seen, and only Kuat possessed shipyards that were capable of supporting and maintaining more than a handful at a time.
The Executor-class Star Dreadnought, also known as the Super-class Star Destroyer, was the largest model of Star Destroyer ever built by the Galactic Empire. It was usually referred to as a Super Star Destroyer, and consisted of the sub-models Executor I-class and Executor II-class. 19,000 meters long, it was used as a command ship and had over 5,000 turbolasers and ion cannons.
The Mega-class Star Dreadnought, also referred to as the Mega-class Star Destroyer, was the capital of the First Order and its Supreme Leader. At 13,000 meters in length and a wingspan of 60,000 meters, the Mega-class was wider than it was longer. The sole example of the model the Supremacy was used by Supreme Leader Snoke and the First Order Navy to attack the Resistance.
Battlecruisers
There were multiple examples of Star Destroyers that were classified as battlecruisers during galactic history. The Maelstrom-class battle cruiser was used by the Galactic Republic during the Clone Wars, was primarily mothballed by the Galactic Empire, and at least one example, the Simoom, was used by the Alliance to Restore the Republic. The Maelstrom-class was considered to be a proto-Star Destroyer, and was armed with assault concussion missile launchers, heavy cannons, and other weaponry. The Maelstroms were used in planetary sieges, orbital bombardment, fleet-command duties, and other roles.
The Secutor-class Star Destroyer, also identified as the Secutor-class battlecarrier, was another example of a battlecruiser in the Star Destroyer design family. Being multiple kilometers in length, the Secutor was used as a carrier and command ship by the Galactic Empire. It was possibly the largest starfighter dedicated vessel in the Imperial Navy. The Empire’s successor state, the First Order, widely deployed the Resurgent-class Star Destroyer, alternatively designated as the Resurgent-class Battlecruiser, during the Cold War and the First Order-Resistance War. The Resurgent was a 2,915 meter-long warship that featured advanced weaponry and systems.
According to the Anaxes War College System, the Sith Eternal‘s Xyston-class Star Destroyer, at 2,406 meters, was a battlecruiser. The Xyston was a model of Star Destroyer that was based on an upscaled Imperial I-class design. The Xyston-class possessed heavy weaponry, including the axial superlaser cannon which had the capability of destroying entire planets.