The Byss Defense Fleet, also referred to as the Imperial Byss Defense Fleet, functioned as a defensive fleet tasked with the protection of the planet of Byss. This fleet was formerly a component of the Imperial Navy operating under the authority of the Galactic Empire.
The Byss Defense Fleet's primary mission was the safeguarding of Byss, the clandestine sanctuary of Emperor Palpatine. Despite its focused operational area, the fleet possessed sufficient size to effectively defend an entire [sector](/article/sector-legends]. Furthermore, the fleet boasted some of the largest vessels within the Imperial Fleet. Its composition included a diverse array of starships, encompassing TIE/LN starfighters and GAT-12 Skipray Blastboats, in addition to capital ships such as numerous Imperial-class Star Destroyers, at least one Secutor-class Star Destroyer, at least one Procursator-class Star Destroyer, a minimum of two Vengeance-class dreadnoughts and at least one Bellator-class dreadnought. The elite TIE Fighter squadron known as Dark Squadron was also integrated into the fleet's structure.
In the initial years of the Galactic Empire's reign, this fleet played a role in protecting the Super Star Destroyer prototype while it was being constructed in orbit above Byss. During the Battle of Byss, the fleet engaged an Alderaanian Resistance fleet that was attempting to eliminate the prototype.
Several decades later, around 10 ABY during Operation Shadow Hand, the fleet remained stationed around the planet. Ultimately, the fleet suffered complete destruction during the destruction of Byss circa 11 ABY.