** [[MadScientist Borborygmous Gog]] was the BigBad of the first half of the series. A Shi'ido changeling who once served the Empire, Gog and his partner Mammon Hoole worked on the world Kiva. When Gog realized their experiments would result in the extinction of all life on Kiva, he reported this to the Emperor and carried on with the experiments while concealing the truth from the more moral Hoole. He had no compunction letting Hoole [[TheScapegoat take the blame]], either. Gog would continue Project Starscream, creating bioweapons that included, among others, a living planet that devoured organic life; a machine to trap people in their worst nightmares; and an essence stealer that trapped the life force of sentients in a crystal matrix. To [[ForScience test them]], Gog regularly unleashed them on innocents while cataloging the results. When his "masterpiece," the living bioweapon Eppon, chose to side with [[TheAtoner Hoole's]] family against Gog, Gog simply killed him without remorse. He also funded Dr. Evazan’s research (see below). Combining his brilliance with an utter lack of morals, Gog sought to master the Force and achieve scientific perfection- even if the Galaxy had to burn behind him.
** [[MorallyAmbiguousDoctorate Dr.]] [[MadScientist Cornelius]] [[DeadlyDoctor Evazan]] [[Literature/TalesFromTheMosEisleyCantina brags to Luke Skywalker]] that his crimes have given him the death sentence in twelve systems ([[Film/ANewHope "He doesn’t like you…I don’t like you..."]]). A SerialKiller and thug with delusions of grandeur, Evazan claimed countless victims with his depraved experiments. When his Aqualish partner Ponda Baba lost an arm to Obi-Wan Kenobi after threatening a young Luke, Evazan kidnapped an Aqualish Senator to have Ponda's mind transferred into the Senator's body, obliteraring the senator's consciousness. When this went wrong and Ponda was erased and replaced with the Senator's mind, Evazan had no remorse. Joining Project Starscream, Evazan moved to the world Necropolis where he tried experimenting to bring the dead back to life. For this end, Evazan even murdered and attempted to [[WouldHurtAChild murder children]] to reanimate and fuel his personal ZombieApocalypse.
* FridgeBrilliance: The DarthVaderClone thinks he's really Vader but is less scary and effective and more petulant than Darth Vader - ''like Anakin''. Which is another reason why Vader [[ThereCanBeOnlyOne hated him on sight]]! It's known from elsewhere in the ExpandedUniverse that he hates ''himself'' more than anything or anyone.
** FridgeLogic: Why didn't Yoda do anything about the Children? At the time it was written it was assumed that Yoda had been there for a very long time and would have seen the NoPartyLikeTheDonnerParty situation brewing and spilling over, it was happening within walking distance of where he lived and they ''saw him watching them''.
* GrowingTheBeard: For some, ''Army of Terror'', in which the series wrapped up the Project Starscream storyline and moved away from old formulas.
* NauseaFuel: ''The Planet Plague'''s BlobMonster [[spoiler: The Virus]] and Spore, especially.
* TooCoolToLive: Captain Hajj.
* TheWoobie: Both Tash and Zak. They're twelve and thirteen and lost everything six months before the first book, when Alderaan was destroyed. Every time they pick up material possessions these end up getting lost along with whatever ship they currently have. [[OrphansOrdeal Their guardians are grudging]] at first, and keep dragging them across the galaxy into danger. Tash is weird and Force-Sensitive, which gets her blamed sometimes for things that aren't her fault, and has [[PleaseDontLeaveMe abandonment issues]]. She wants to withdraw and be away from everything but feels like she can't because [[PromotionToParent someone has to look out for Zak]]. Zak has BadDreams and misses their parents terribly.
** StoicWoobie: Hoole.