- "The Dioskouroi are my finest agents. Totally unstoppable."
- ―High Admiral Tharkus
The Dioskouroi were an exiled branch of the Shi'ido species. Their molecular construction allowed them to absorb large amounts of energy from the surrounding atmosphere and transmute it to matter of any form. While most of the Shi'ido had always maintained neutrality in the affairs of the Galactic Republic and Galactic Empire, the Dioskouroi had no such scruples. In the aftermath of the Nagai–Tof War, the Imperial High Admiral Tharkus hired the Dioskouroi twins Kastor and Pollux to act as his personal spies. In their natural form, Dioskouroi were cadaverous beings with bluish, translucent skin.
- The Heart of the Jedi (First appearance) (Cancelled)