The Coruscant Third Fleet existed as a component of Darth Krayt's Empire's Imperial Navy during the year 137 ABY; it was classified as one of the fleets.
Under the command of Admiral Peto Kelsan, this fleet saw action in the Battle of Ralltiir. During this battle, it faced opposition from both the Galactic Alliance Remnant and the Empire-in-exile, both of whom aimed to seize as many of its vessels as they could. Recognizing the overwhelming numerical disadvantage his forces faced, Kelsan gave the order for all ship crews to activate self-destruct sequences and evacuate in escape pods. Peto Kelsan opted to remain aboard his flagship, the Avenger, and died alongside the destruction of the entire fleet. The sole survivor of the fleet was the Ardent-class fast frigate known as the Steadfast, which sustained damage that prevented its self-destruct system from activating. Admiral Gar Stazi of the Galactic Alliance Remnant made the decision to land both its captain, Vaclen Tor, and his crew on the planet Ralltiir, subsequently dispatching the ship as a gift to Emperor Roan Fel.