The top goons are Grand admiral Thrawn, Warlord Zinsji, admiral Daala , Darth Vader , former emperors hand

Mara Jade, and admiral Fyyar. They use WMDs to show their might. The most imposing weapon maybe a tie between The Death Star,

the World Devastators ,and the sun crusher. Their unfair laws and regulations made the galaxy a dangerous place. 

Since  the death of the emperor their space has dwindled into a small corner of the galaxy. After Thrawn's  attacks admiral Fryyar

tried a last ditch assault  on the Jedi academy on Yavin 4. After Kyle Katarn killed Fyyar Rouge squadron destroyed his ship the Doomgiver.

Then Katarn killed Dark Jedi Dessan at the academy. After that  a few other imperials tried to restore their former glory. They

failed miserably. Then the Vuzzan Vong attacked