The Skulls were a mercenary starfighter force known for both the skills and ruthlessness of their members. The organization had been involved in numerous conflicts since the time of the Clone Wars.
Rather then being fixed to a single planet or location, the Skulls traditionally operated form a starship, with secondary planetside faculties dependent on their strengths and operational needs. Their flagship was the Laughing Skull, an old Venator-class Star Destroyer that was salvaged and refitted. Previous ships in the same role included a variety of modified freighters and light warships, none of them as suited to the role as the most recent ship.
In order to join the Skulls, a pilot needed to demonstrate that they could measure up to the organization's requirements for piloting skill and combat capability, as well as being able to uphold the "standards" of ruthlessness in combat that they expected. Pilots were expected to provide their own aircraft; a small selection of craft were in reserve for pilots without machines.
The Skulls' organization was somewhat confused. There was no standardization of ships, each pilot instead operating whatever starfighter they preferred or have available. Individual fighters remained the property of their pilots, with a provision that they would also provide for some of the support and maintenance costs for their ships. The only requirements for equipment standard was that the Starfigther was painted with a black basecoat, and that it prominently displayed the Skull Insignia.
Fighters were usually organized into ad hoc squadrons based on the capabilities of the ships; similar types were grouped together, or ships of different types with the same abilities. In such cases, leadership would typically be assigned to the pilot who had been with the organization the longest, if not necessarily the most experienced pilot.
The Skulls were first recorded about 60 BBY, participating in various small conflicts of the time. Their exact date of founding was unclear; artwork and images onboard their Flagship depicted craft in Skull markings as far back as the Mandalorian Wars, however, the authenticity of these images could not be verified.
During the Clone Wars, the size of the unit expanded dramatically, as did its operations. New pilots joined the force as the conflict grew, adding considerably to the range of craft and skills available. The organization was known to have fought on both sides of the conflict at various stages, preferring the Separatists during the early stages of the war, and the Republic during the latter.
Following the war, the Skulls moved to the outer rim, fearful of the effects that the 'new order' would have on their operations. Initially neutral during the Galactic Civil War, the Skulls preferred to work for smaller governments and agencies. A lot of time was spent in the Corporate Sector, chasing smugglers and quashing resistance movements. With the fall of the Empire, the Skulls began taking a more active part in the conflict, working for both the Rebels and the post-Imperial factions.
In 23 ABY a Hawaiian Shirt-Wearing Rebel Pilot was dispatched to try and infiltrate the Skulls for and try to bring them firmly over to the New Republic's side. The operation was unsuccessful; while the pilot showed that he had the degree of piloting skill and knowledge needed to meet their standards and he had painted his ship (and R2 unit) black, they found that he was, simply put "too nice" for them. However, they also found him to be amusing, so they let him go back unharmed.
This unexpected display of humor had one upside; in 27 ABY, the Skulls unexpectedly (and uncontracted) began launching attacks on Yuuzahn Vong-held worlds, as well as assisting republic forces in various battles. While the Skulls themselves suffered severe losses, the organization survived the war.
In the post-war period, the Skulls had begun to rebuild and reorganize, greatly increasing their strength. By the start of the Corellian Insurrection, the unit was at the strongest that it had ever been.