- "Some say that war is the beginning of civilization. On Onderon, this was certainly the case, though it was a civilization that took a very peculiar form."
- — Arca Jeth
Onderon is the primary planet in the system of the same name. It has a temperate climate and was home to a primitive race of humanoids before Human colonists arrived. It has four moons. The primary moon, Dxun, orbits very close to the planet and every year, during Dxun's summer season, the atmospheres of Onderon and Dxun connect, allowing the vicious Dxun beasts to set foot on Onderon and settle there.
The planet is largely unsettled aside from the walled city of Iziz, but has been the location for several wars and battles. In current times, the planet was picked by Jedi Master Faarel Blackthorne to be the home of the Jedi Order's academy to replace the one that was lost when the Empire retook Coruscant.
The Onderon system, also called the Japrael system, is home to the planet Onderon and two other planets. It is centered around the star Prael.
To help protect the Jedi on Onderon, the system has been seeded with early warning satellites that were provided as a gift by Juoi.
- Ov Taraba - One of the most prominent, and expensive, universities on Onderon. It was established in roughly 4,000 BBY.
- Iziz Royal Palace - The Iziz Royal Palace was home to the royalty of Onderon in the city of Iziz. It is accessed by the Sky Ramp, which connects directly to the Merchant Quarter. There was a great wall that was once used to protect against the Beast Riders, but essentially became obsolete following the marriage of Oron Kira and Princess Galia.
- Jedi Temple - The Jedi Temple of Onderon is located in the wilds of the planet and designed to work with the surrounding area as much as possible so as not to disrupt the flow of nature. It is also the current headquarters of the Jedi Council.
- Fortress Kira - Fortress Kira was the stronghold of the Kira family on Onderon. It is located far from Iziz.
- Boma Beast - Also simply called "Bomas," these huge, yellowish-green reptilians roam the jungles of Onderon and Dxun. They have ferocious teeth and a body-type resembling a bear.
- Dragon-Bird - A vicious and deadly avian that is popular with locals. They inspired the appearance of dragon-bird robot drones, which are commonly used as target practice by local pilots.