The Laughing Skull was a Venator-class Star Destroyer that serves as the command ship and mobile headquarters of the mercenary squadron known as the Skulls. For some reason, it was been nicknamed the Winged Minibus of Doom, one of several ships to earn the title.
Originally known as the Thunderlord, the ship initially served as a part of the Grand Army of the Republic. Its baptism of fire came in 20 BBY when it served as a part of the Republic force that liberated Shia Mocksae from the Separatist Forces. The ship acquitted itself well, being responsible for the destruction of two enemy ships, as well as damaging Pango Bobo's flagship, the Big Fish.
The ship served with the Republic's Army for the rest of the Clone Wars, taking part in numerous battles. With the formation of the Galactic Empire, it was folded into the Imperial Fleet along with other survivors of the class. Sometime after this, the ship was damaged in battle, one of its main drives destroyed and its hull punctured. Given the phasing out of the class in favour of the newer Victory and Imperial classes, the Thunderlord was mothballed rather than being repaired.
Well, the wiring's got numerous shorts, the atmosphere is thinning, there's numerous leaks, there's condensation in vital systems and the whole thing's full of obsolete hardware. And that's before we mention the missing engine or the big hole in the top
—Arb Itary on the ship's status
The derelict ship was located by the Skulls at some point around 23 ABY, the result of a lengthy hunt for a new command vessel. The damaged ship, preserved by the vacuum of space, was towed to a drydock where it underwent a considerable repair and refit to rebuild its damage system, bring it up to more modern standards and adapt it for the Skulls' use.
Despite the considerable expense involved, the Skulls' leader, BD Andrews, believed that it would be worth the effort for the expansion to their capabilities. Until this point, the Skulls had been reliant on several older ships, often converted transports, as bases of operation, but none had measured up to their requirements. With the arrival of the new ship, rechristened to the Laughing Skull' by Andrews, the Skulls boasted a powerful warship that was capable of supporting their entire force. Their remaining ships were all sold off by Andrews, the profits going to finance the reconstruction.
Entering service in 25 ABY, the Laughing Skull immediately proved to be a success. The ship greatly expanded the mobility and capability of the Skulls' operations. While rarely engaging in combat itself, on the few occasions that it did engage other vessels it was victorious through its superior firepower. When the Skulls entered into the Vong war on the Republic's side, the Ship served as their base of operations throughout.
Since the war, the Laughing Skull has continued in its role. Recently, Andrews has made some comments regarding "upgrading" the ship or replacing it all together, however nothing has yet come of this.