Black Sun was a pervasive galactic crime organization that was essentially the Star Wars Mafia because although the Hutts already fulfill this role, their body mass makes their drive-by shootings somewhat hard to take seriously. Black Sun was involved, appropriately enough, in every form of illegality it could find, and several that it couldn't. This latter implausibility was made possible through multiple front companies whose complexities were beyond mortal ken. Its most prominent members—meaning those two Star Wars fans know most about—were Xizor and Guri, who operated during the Galactic Civil War.
Black Sun was divided into nine subdivisions each headed by a Vigo, which for all intents and purposes may be considered no more than a spectacular typo for Don, because let's face it, this is just the Space Mafia we're talking about. Ruling over the nine Vigos was the Force-father, who....look, there are only so many Mafia jokes available and let's not demean ourselves by indulging in them please? Black Sun equals Mafia. If you don't believe me, then read Shadows of the Empire.