Abersyn symbiotes were a species which fed on the brain stem of sentient species. They had to be fed into a plasma furnace in order to keep them in a quiescent state, though a regular exposure to a plasma vent was proven to have the same effect on them. They were known for being responsible for the death of many historical empires; therefore, having a specimen was banned by Imperial decree.
During her time as a doctoral student in the University of Bar'leth, Chelli Lona Aphra was studying and exploring the planet of Boothi XII looking for an incredible discovery. After finding nothing on Boothi XII, Toob-Nix, Aphra's doctoral supervisor, showed her a full nest of Abersyn symbiotes in his personal chamber, telling her why he hated her so much and that he would never give her his approval to get the doctorate. As revenge, Aphra stole the whole nest with the help of Sana Starros and made it appear as if she had finally found the Abersyn symbiotes on Boothi XII. As a part of the Imperial protocol, the symbiotes were disintegrated right away.
On Ktath'atn, the Queen of the planet was an entity of Abersyn symbiote who has possessed a humanoid through Force drain and kept several members of her species that she used to control her collection. She attempted to use them on Aphra and Luke Skywalker as a feigned "dessert", but proved unsuccessful when Aphra realized the trap and escaped with the Padawan. Aphra later found a large colony of the symbiotes and 0-0-0 directly implanted one in Black Krrsantan so he would go berserk and attack the Queen's followers.
- Doctor Aphra 1 (First appearance) (Appears in flashback(s))
- Doctor Aphra 2 (Mentioned only)
- Doctor Aphra 5 (Mentioned only)
- Star Wars 31
- Doctor Aphra 7
- Star Wars 32
- Doctor Aphra 8
- Star Wars 33 (Indirectly mentioned only; in the opening crawl)
- Doctor Aphra 10 (Indirect mention only)
- Doctor Aphra 38 (Mentioned only)
- Doctor Aphra 1 (Mentioned only)