The Brilliant was a Star Destroyer serving the Imperial Navy during the Galactic Civil War. It was commanded by Admiral Sander Delvardus.
It would later become the home for his mistress, Seledra-Zin, as he sought a cure for her comatose state.
Sources
The Imperial Warlords: Despoilers of an Empire: Part 2 on StarWars.com (original link is obsolete)