Executor

The Dreadnought-Class Super Star Destroyer or the "Executor" was the personal flagship of Dark Lord of the Sith, Darth Vader- and acted as a base for his apprentice Galen Marek while it was being constructed. The Executor is a impressive 19,000 meters long and was conisdered the "Largest Warship The Galaxy Had Ever Seen". By 0 ABY, it was moved into a Starship Yard that was hovering over Fondor, and was oversaw by Admiral Amise Griff. After a attempt by some traitor Imperial Admirals to destroy the Executor, which ultimately failed, Darth Vader used his new flagship in the Yavin System. However, his new weapon failed the attempt to destroy the Rebel Base of Yavin 4, killing Admiral Griff in the process.

History
It was on the Executor that Galen Marek received his first proper mission from his master- Lord Vader. The Sith Lord ordered him to go to the TIE Fighter Construction Facility over Nar Shaddaa, which Jedi General Rahm Kota was attacking with his Militia. Later, in 4 ABY, the Executor would be destroyed by the Rebellion's Fleet in the attack on Endor by crashing into the Death Star II.