The Assassin was an Imperial I-class Star Destroyer. Assembled at Kuat Drive Yards, it served the Galactic Empire until the time of the Yuuzhan Vong War. After Tak Sakaros rescued Arba the Hutt on Nar Shaddaa, losing all of his Star Destroyers in the process, the Hutt gangster repaid the favor by "obtaining" several Star Destroyers for his friend, including the Rampart, Overlord, and Assassin.
The Assassin remained part of Tak's fleet until 87 ABY, when the fleet and all its craft were confiscated by Rin Sakaros and turned into the Prime Fleet of the Golden Empire. In the early years of the Golden Empire it regularly accompanied the Sith Star, but was also sometimes dispatched at the head of small battle groups. The Assassin was a front-line warship during the Great Liberation and Keltrayu's command ship during the harrowing but ultimately successful Battle of Yin. It participated in the Battle of Tizgo V and the Capture of the Vall`to sector.
Following the war, the Assassin was regularly assigned to system patrol, though it sometimes took part in expansion campaigns, including the Conquest of the Chiss Ascendancy, where it was Sorrik's command ship during the Battle of Kinoss. It was Tariun Sakaros's command ship during the calamitous Battle of Lebyool and was assigned to Legate Salome Hrek's command during the Vagaari War shortly thereafter. It remained with the Prime Fleet during the Nightmare War, but consequently fought in the Battle of Dolomir.
When Breek Zagrev became a Royal Executor and was granted a fleet of her own in 154 ABY, the Assassin was the largest ship assigned to her command, with the Chiss Sak'anto'nussos as captain. She used it often for Bisecting Drives.