List of fictional alien species: R

Name	Source	Type
Raas	Master of Orion III
Rabotevs	Harry Turtledove's Worldwar book series	A subject species of the Race in the Worldwar book series
The Race	Moreau series	Amoeboid
The Race	Harry Turtledove's Worldwar book series	Reptilian, often called "Lizards" by humans due to their appearance.
Rachni	Mass Effect
Radicles	OK K.O.! Let's Be Heroes
Raiel	Peter F. Hamilton's Pandora's Star
Rako-Gorda	Utopia
Ram Pythons	Battlelords of the 23rd Century
Rancors	Star Wars
Raptors	Nexus: The Jupiter Incident
Raxacoricofallapatorians	Doctor Who
Reapers	Doctor Who
Reapers	Mass Effect
Reapers	X-COM: UFO Defense
Regul	C. J. Cherryh's Alliance-Union universe
Relgarians	Farscape	Humanoid
Remans	Star Trek	Humanoid
Re'ol	Stargate SG-1	Humanoid
Replicators	Stargate SG-1	Artificial lifeform. Two variants are known to exist, in a small mechanical insect shape as well as full humanoid.
Re'tu	Stargate SG-1
Rigellians	Lensman books	Barrel-shaped with four tentacular arms and four stubby legs
Rigellians (including Kang and Kodos)	The Simpsons
Riim	The Voyage of the Space Beagle by A. E. van Vogt
Rills	Doctor Who
Rimerunner	Expedition
Rimmer	Red Dwarf	Hologram-humanoid
Risians	Star Trek	Risians are extremely open and will freely share their planet, and even themselves, with vacationers – a practice known as "Jamaharon".
Robotech Masters	Robotech
Rodians	Star Wars
Roger the Alien	American Dad!
Rogue Simulants	Red Dwarf	Humanoid
Romulans	Star Trek	Humanoid
Rull	The War against the Rull by A. E. van Vogt
Rutans	Doctor Who
Ryouko Asakura	The Melancholy of Haruhi Suzumiya	Humanoid interface
Ryqril	Timothy Zahn's The Blackcollar