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- Rannians - The Rannians of Rann are an ancient nearly sterile race of technologically advanced humanoids. They are represented by Alanna Strange wife of Adam Strange. located in the Polara star system.
- Ranx the Sentient City - Ranx is an ancient Berserker construct in the form of a city. Ranx can observe anything in its vicinity, and can also control local gravitational forces.
- Ravagers of Olys -
- Red-Moon Gods - Atlantean survivors of the city of Challa-Bel-Nalla, then ruled by Lord Daamon (an ancestor of Deimos), formed an alliance with an alien race they called the Red-Moon Gods. These aliens provided the Atlanteans with advanced technology that Travis Morgan would later discover in New Atlantis.
- Red Saturnians - (see Saturnians)
- Reflektorrs - The Reflektorrs are a race of psionic parasites consisting of pure psychic energy, they were discovered feeding on natives of Apokolips.
- Replikons -
- Reach - The Reach are an ancient militaristic race who control space Sector 2, they have an ancient non-aggression pact with the Oans, and are the creators of Jaime Reyes' (Blue Beetle) scarab. They are also the second oldest race in the universe behind the Maltusians.
- Rhoon - Rhoon is a planet split between science and elemental sorcery, with magic users segregated to the Sorcerer's Isle. They are represented by Green Lantern Hollika Rahn.
- Rigellians - The Rigellians are a violet skinned, four armed race of noseless amphibians, who fled their own dying world untold years in the future. They were welcomed by humans living on planet Earth in a time when the sun appeared to have become a red giant. A civil war takes place when the Halflings, offspring of Humans and Rigellians overthrow their forefathers.
- Roboticans - The Roboticans of Robotica are a machine civilization led by C.O.M.P.U.T.O. which is native to the 30th Century.
- Roguians - Shy race from the planet Rogue in the Vegan System. Soon after birth they learn to produce a natural force shield that hides them even from each other. Elu of the Omega Men is a Roguian.
- Rulanns - One of two races from Rojira which resemble star-fish.
Read more about this topic: List Of Alien Races In DC Comics