Black Sun is an evil crime syndicate among the Star Wars galaxy.
The Clone Wars
During the Clone Wars, the focus of the Jedi Knights on defeating the Separatists meant a decline of law enforcement, particularly in the sparsely patrolled Outer Rim Territories. This allowed criminal elements, like the notorious Black Sun syndicate, to flourish. The Black Sun's tentacles reached across many worlds. Many of the organization's operatives had no idea that they were benefiting Black Sun, so layered and intricate were the fronts that the syndicate hid behind.
During the time of the Clone Wars, Black Sun was led by a cabal of Falleen nobles, under Xomit Grunseit, who operated out of a well-defended fortress on Mustafar. During the war, they were coerced by Darth Maul into joining the Shadow Collective. After Savage Opress murdered Grunseit and his ruling council, Ziton Moj assumed control of the faction and pledged allegiance to Darth Maul.
Galactic Civil War
The ruling mantle of Dal Perhi was passed down to the Falleen prince Xizor during the Galactic Imperial reign, an event in which led Black Sun to be so powerful under the Falleen's leadership that it almost rivaled even Darth Vader and Emperor Palpatine.
With an uncountable amount of credits and loyal mercenaries, Black Sun rose to be one of the most feared and infamous crime syndicates in the entire galaxy, as they ruled the under world of Corusant However, Xizor and Vader had a passive aggressive relationship. Though they hated each others' guts (as Vader ordered the deaths of Xizor's family when they were infected with a spreading virus) they refused to show their hate to the public, especially Palpatine.
In an act of revenge, Xizor attempted to assassinate Luke Skywalker in order for Vader, who too was searching for the Jedi, to look bad through the eyes of the Emperor. The several assassination attempts eventually led to the death of Black Sun's clever ruler. So, his neice, Savan, attempted to bring the syndicate back to its glory, all the way to the end of the civil war when Vader, Palpatine, and the Empire were destroyed for good.