Excalibur

Emperor Palpatine's personal C-3 Passenger Liner during the Galactic Civil War. The ship was used to transport the Emperor and his dignitaries to Endor, but traitor forces led by Grand Admiral Zaarin attacked the ship. However Grand Admiral Thrawn arrived and deployed starfighters led by Maarek Stele who drove off Zaarin's forces. The Excalibur then transferred the Emperor to the Super Star Destroyer Executor which delivered him to the Endor system.

=Sources= http://www.ptheriault.ca/swdatabank/databank/evolutions/3-5.asp
 * Star Wars: TIE Fighter
 * Star Wars Databank,