Silooth (Star Destroyer)

Fi was the personal Star Destroyer of Grand Admiral Peccati Syn. He named it after the High Galactic word "fi," used by the clergy of his Sacred Way religion. It was vaporized by Admiral Ackbar's forces during the liberation of Kashyyk, killing both Syn and Merili.

Behind the scenes
In a section of the Grand Admirals article that was cut, author Dan Wallace mentioned that the Fi was renamed the Silooth, presumably due to him converting from the Sacred Way to the Church of the Dark Side. However, as the section was cut, it is not official.