
In Jedi Academy (14 ABY), the main villains are the Disciples of Ragnos a Sith cult, discovered and led by Tavion (Desann's former apprentice). It made one desperate last bit for power in 14 ABY (relying on child recruits), but failed. With the destruction of the Doomgiver and failure of Fyyar/Desann's plan, the Empire Reborn lost most of its military resources and had to go back into hiding (becoming little more than a slave trading group). He eventually recruited Galak Fyyar (an officer in one of the splinter factions), Desann (fallen student of Skywalker's Jedi Academy) and a few others to his cause. After the death of the Emperor he went into hiding, and infiltrated the New Republic (and some of the Empire splinter factions), trying to build up his own power base. The Empire Reborn was a faction led by Hethrir, former student of Darth Vader, and senior (if secret) figure near the top of the Empire's criminal justice system. The Imperial forces in Jedi Outcast (12 ABY) were retconned to be the Empire Reborn of The Crystal Star. all tried to keep their power, while struggling with each other for supreme power.

Without him, and the central authorities, regional governors, military leaders etc. Which makes sense the Empire was a huge military, industrial and governmental system, held together by the ruthlessness of the Emperor. Between the death of the Emperor in 4 ABY and the stabilisation of the Imperial Remnant around 20 ABY the Empire wasn't really a single thing, but a whole mess of different factions under the control of different leaders, warlords, politicians and dictators.
