- "Ancient warriors built the Great Temple more than 5,000 years ago."
- ―Tour the Great Temple on Yavin 4
The Massassi were a mysterious species that built enormous stone temples of unknown purpose on the fourth moon of Yavin some five thousand years before the rise of the Galactic Empire. Whether the Massassi had evolved on Yavin 4 or were a slave race in thrall of the Sith and brought to that moon was unknown, although the latter seemed more likely. Sometime after finishing their temples, however, they went extinct. At some point, either as part of the original intent of the building or through ulterior additions, the Jedi splinter group known as the Ordu Aspectu used one of the Massassi temples, the Great Temple, to store information, including a map room that gave directions to their hidden headquarters.
After their extinction, the Massassi were mentioned in a travel advertisement written by a Special Galaxy Reporter who had investigated the Great Temple ruins after the Alliance to Restore the Republic abandoned the jungle moon.
- A New Hope: The Princess, the Scoundrel, and the Farm Boy (Mentioned only)
- Star Wars: A New Hope junior novelization (Mentioned only)
- "Grounded"—From a Certain Point of View (Mentioned only)
- Smuggler's Run: A Han Solo & Chewbacca Adventure (Indirect mention only)
- Doctor Aphra 2 (Mentioned only)
- Doctor Aphra 3 (Mentioned only)
- Journey Through Space (First mentioned)
- Ultimate Star Wars (First identified as Massassi)
- Star Wars: The Force Awakens: The Visual Dictionary
- Star Wars: Complete Locations
- Star Wars: Galactic Atlas
- Star Wars: Absolutely Everything You Need to Know, Updated and Expanded
- Star Wars Helmet Collection 76 (Databank A-Z: Yavin 4)
- Star Wars: The Complete Visual Dictionary, New Edition
- Star Wars: How Not to Get Eaten by Ewoks and Other Galactic Survival Skills