Thats not even the biggest one...
Eclipse-class Star Dreadnought
The 16 kilometer long Eclipse-class Star Dreadnought was larger than the Sovereign-class ships and much more massive than the longer Executor-class Star Dreadnought. The first of this class, the Eclipse, became the reborn Emperor's flagship. It was supposedly one of the most heavily armed ships in the history of the Star Wars galaxy. It carried thousands of turbolaser and heavy turbolaser cannons. It also had powerful shields and heavy jet-black armor, making it difficult to destroy in space combat. The most important feature was a superlaser cannon located on the bow of the Eclipse. Although it was not as powerful as the superlaser on the Death Star, it was capable of blasting through a planetary shield and cracking a planet's crust. According to the WEG RPG stats, Eclipse carried 600 TIE Interceptors and 96 TIE Bombers, divided into 58 squadrons; for ground assault, it carried 150,000 Imperial Stormtroopers, 100 AT-ATs, and five prefabricated bases. The Eclipse was said to be crewed by over 700,000 personnel.
The power of the Eclipse's superlaser as described is self-contradictory. It has been described as 2/3rds the power of the Death Star's prime weapon. Such a weapon would be more than sufficient to destroy a planet, yet it was also stated that the Eclipse's superlaser was not powerful enough to destroy a planet. There is some speculation as to whether the 2/3rds number refers to the magnitude of the energy release as opposed to the total value; this would put the main weapon below the threshold necessary to destroy a planet.
The Eclipse was destroyed along with the reborn Emperor Palpatine when Luke Skywalker and his sister Princess Leia managed to disrupt the Emperor's control of a titanic Force Storm, a massive conflagration of Dark Side energy that he had summoned in order to wipe out the massed New Republic fleet. Afterwards, a second Eclipse-class ship was built, dubbed the Eclipse II. Above the planet Byss, R2-D2 took control of the Eclipse II's computers and then sent it on a collision course with the Galaxy Gun superweapon. The explosion destroyed both the Eclipse II and the Galaxy Gun. One last projectile was pulled by Byss' gravity and hit the planet, destroying it.
Heres a page with a pic...a much better looking ship I think.
Eclipse-Class Super Star Destroyermaybe a pic or two?
