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- Jaquaans - Little is known of the Jaquaans of planet Jaquaa. Their sole representative in the 30th Century is Doctor Gym'll the staff doctor of the Legion of Super-Heroes.
- Jirenn - A humanoid race from Rojira which represent the Green Lantern Rori Dag.
- Junoans - The Junoans of asteroid Juno are a race of technologically advanced humanoid aliens. The Junoans are protected by an Atlantean exile named Zarl Vorne who gained Kryptonian equivalent abilities when in close proximity to the Juno asteroid.
Read more about this topic: List Of Alien Races In DC Comics