Some Rahi are able to wear powerless Kanohi, which can be infected by Kraata to subject the wearer to the Makuta's influence. Rahi may also be controlled by beings with the power of Rahi Control, or by users of the Mask of Rahi Control.
Most of the Rahi of the Matoran Universe were created by the Makuta, whose technique involved blending various Viruses in vats of Liquid Protodermis. Later, as the Brotherhood of Makuta became corrupt, they began to create Rahi for the organization's own use. A few Rahi in the Matoran Universe predated the Makuta, having been created by the Great Beings or other, earlier factions like the Hand of Artakha. A few other species of Rahi are the result of Energized Protodermis or other factors acting on pre-existing Rahi, sapient beings, or the environment. Many Rahi made the planet of Spherus Magna their new home after the operating systems of the Matoran Universe were rendered inoperable.
- Acid Flies - Small insect Rahi that live on the Southern Continent.
- Air Serpents - Acid-spitting Rahi which inhabited Karda Nui, and which the Toa Mata at one point fought against.
- Archives Beast - A beast that dwells in the Onu-Metru Archives.
- Archives Mole - Used to dwell in Po-Metru.
- Artakha Bull - A swift, strong, hostile, and noble centaur Rahi that is good at tracking. Believed to live in Artakha.
- Ash Bear - Large bear-like Rahi .
- Graalok - An Ash Bear that befriended Lewa.
- Blade Burrower - One of the most powerful Rahi known in Onu-Metru. Created by Makuta Mutran.
- Bog Leech - A leech Rahi known to live in swamps.
- Bog Snake - A serpentine Rahi that lives in swamp regions.
- Borer Worm - A worm Rahi.
- Brakas - A mischievous monkey Rahi that is commonly found in Le-Wahi.
- Burnak - A quadrupedal Rahi found on Voya Nui.
- Cable Crawler - A Rahi that lives in the cables of Le-Metru.
- Catapult Scorpion - A scorpion Rahi that can launch balls of magma from its tail.
- Cave Fish - A fish Rahi that makes itself seem bigger than it really is.
- Chute Lurker - A spider Rahi that hides in chutes to capture prey.
- Cliff Bug - A pesky grasshopper that is found in Ga-Wahi.
- Cliff Screecher - A bat-like Rahi native to Odina.
- Colony Drone - A small biped species of Rahi that were once slaves of the Visorak.
- Crystal Climber - Large Rahi that live atop Knowledge Towers and eat Ice Bats.
- Crystal Serpents - Serpents who live in Artakha's bays, mostly dormant.
- Dagger Spider - A spider-like Rahi from Voya Nui.
- Dermis Turtle - A small, humble, turtle-like Rahi that uses a mysterious ability to predict the weather.
- Devourer - Small Rahi that travel in swarms and eat inorganic Protodermis.
- Dikapi - A flightless desert bird Rahi.
- Doom Viper - A multi-headed snake Rahi with poison breath created by Makuta Chirox.
- Dust Darter - Small Rahi that live in Karzahni's realm, they eat Protodermis and attack the Matoran's armor.
- Dweller in the Deep - A gigantic, fearsome Rahi that has a jaw big enough to swallow the Great Temple, though it chooses to live under it instead.
- Electric Bug - An insect found in Le-Wahi that attacks with high-voltage bolts.
- Electric Spider - An arachnid that sprays jolts of lightning.
- Energy Hound - Canine-like creatures with tracking sense.
- Fader Bull - A bull Rahi that can teleport.
- Feeder Worms - A species of Rahi that produce a repulsive, slimy sound from within their nests.
- Fenrakk - A large spider-like Rahi, which is native to Voya Nui. One specimen was enlarged, and forcibly fused to Vezon.
- Fikou - A dangerous tree spider Rahi that was commonly found in Le-Wahi.
- Fireflyer - Flying Rahi that have bites that make one feel like they are on fire.
- First Rahi - Massive, monstrous sea beasts created by the Great Beings.
- Frost Beetle - A large, intelligent beetle Rahi.
- Frost Leech - A small creature which absorbs heat from other beings.
- Furnace Salamander - Reptile Rahi that reside in Ta-Metru.
- Fusa - A kangaroo Rahi that was commonly found in Po-Wahi.
- Gadunka - Tiny Rahi that inhabit oceans.
- Gafna - A rodent-like Rahi found on Voya Nui.
- Gate Guardian - A large Rahi that projects a smaller version of itself.
- Ghekula - An amphibious frog-like Rahi.
- Giant Swamp Lizard - A Rahi that resided in Le-Koro.
- Great Temple Squid - Huge water-dwelling creatures native to Metru Nui.
- Gukko - Huge, bird-like Rahi.
- Hahnah - A small crab Rahi found in the depths of the Pit.
- Hapaka - Hapaka were native to the mountainous regions of Mata Nui, where they bounded from rock to rock with sure-footed ease.
- Hikaki - A "Dragon Lizard".
- Hoto - Firebug lizard that lived in Ta-Wahi.
- Husi - An ostrich Rahi.
- Hydruka - Rahi native around Mahri Nui.
- Morak - A blue-colored Hydruka.
- Thulox - A red-colored Hydruka.
- Ice Bat - A bat Rahi that is a nuisance to Ko-Matoran Seers as they knock over their instruments.
- Ice Vermin - A rodent Rahi that travels in packs to attack larger creatures.
- Infernavika - A tiny bird Rahi that lived near Ta-Koro.
- Kahu - A Rahi hawk that lived in Le-Wahi.
- Kane-Ra - A bull Rahi which is also known as the "Bull of Legends".
- Kanohi Dragon - A legendary dragon Rahi that had Kanohi-shaped scales.
- Kardas Dragon - A dragon Rahi that was transformed from an enlarged Fenrakk spider by the Ignika.
- Kavinika - Wolf Rahi used by Matoran scientists to guard certain places and things.
- Keetongu - A large, wise, sentient Rahi that knows how to negate Hordika Venom.
- Keras - A coral crab that can be tamed, and even used as a mount.
- Kewa - Smaller bird-like Rahi that the Matoran can fly on. Commonly found in Le-Wahi and tamed by the Le-Matoran.
- Kikanalo - Massive rhino-like Rahi that live in the Sculpture Fields of Po-Metru. They also live on Voya Nui.
- Mutated Kikanalo - A mutated form of Kikanalo, caused by one being injected with Hordika Venom from the Visorak.
- Kinloka - An experimental Rahi seemed to be a distant relative of the Stone Rat.
- Kirikori Nui - A huge insect-like Rahi.
- Klakk - Flying Rahi created by Mutran with sonic screams that can quell a Makuta.
- Kofo-Jaga - A smaller cousin of the Nui-Jaga. They are drawn to heat sources, but abhor light.
- Kraawa - A Rahi with the ability to absorb any force used against it and use it to grow in size.
- Krahka - A female sentient Rahi that can shapeshift. She is the only free member of her species.
- Kuma-Nui - A giant rat Rahi.
- Lava Ape - A large ape-like Rahi seen in the Voya Nui Online Game.
- Lava Crawler - A Rahi native to Voya Nui.
- Lava Eel - An eel-like Rahi which can melt almost anything.
- Lava Hawk - A bird-like Rahi that lives on Voya Nui.
- Lava Rat - Rat-like Rahi that can burst into flames.
- Lightning Bug - A small insect that can give off an electrical charge.
- Lohrak - Flying serpent Rahi. Too many of them can down even a Toa.
- Longfang - Reptilian predator now native to Metru Nui.
- Mahi - A horned goat-like Rahi that can be tamed.
- Makika - A large and very dangerous toad Rahi that dwells in the caves of Po-Wahi.
- Makuta Fish - A swift fish Rahi who had "The same happy-smile as Makuta".
- Mana Ko - A legendary Rahi believed to be Teridax's ultimate guardian.
- Manas - A giant crab known to serve Teridax.
- Mata Nui Cow - A placid cow Rahi.
- Mata Nui Fishing Bird - Seabird Rahi that roost in the lower branches of Le-Wahi.
- Metru Mantis - A mantis Rahi that feeds on other insects.
- Moa - Bird-like Rahi found in Po-Wahi.
- Muaka - A tiger-like Rahi that can extend its neck forward to grab its prey.
- Mutated Muaka - Muaka mutated by Hordika Venom.
- Mud Crawler - A carnivorous Rahi with acidic breath.
- Necrofinch - A species of bird Rahi that lives in the mountains of Zakaz and can remain singing after it is deceased.
- Niazesk - Species of tiny Rahi created to keep larger Rahi in check.
- Night Creeper - A nocturnal Rahi found in Onu-Metru. Roughly seven feet long, squat, and possessing six powerful legs, it forages for small insects and rodents.
- Nivawk - A hawk-like Rahi, one of which served Makuta Teridax during his rule of Metru Nui disguised as Turaga Dume.
- Nui-Jaga - Large scorpions with stingers that can shoot venom.
- Nui-Kopen - A giant wasp Rahi. They are hostile toward Nui-Rama since they hunt the same prey.
- Nui-Rama - A large flying insect Rahi. They created enormous, towering hives in the Le-Wahi jungle.
- Parakrekks - Large, bipedal amphibious Rahi that feed on the rubble left by the Protocairns.
- Phase Dragon - An unusual Rahi that goes so fast that it can pass through solid objects.
- Pit War Tortoise - A large tortoise Rahi which are part of Carapar's army.
- Pokawi - A small flightless bird of Le-Wahi.
- Proto Drake - A large, graceful amphibious Rahi that lives in Ga-Metru, and on the coasts of Mata Nui. Created by Kojol.
- Protocairn - Rahi which are believed to be villagers from another land that were transformed by the effects of Energized Protodermis. They are now large, amphibious creatures.
- Protodites - Microscopic Rahi that escaped from the Archives.
- Rahi Nui - A mutant Rahi created by the Brotherhood of Makuta.
- Rahi-Matoran Hybrid - A hybrid of a Shadow Matoran and a Rahi.
- Ranama - A fire toad Rahi that lived in Ta-Wahi and preyed on passing Nui-Rama.
- Razorfish - An aquatic creature from Ga-Metru.
- Razor Whale - A whale that lives off the coast of Ga-Metru.
- Red Serpent - A horned serpent that possesses electrical powers.
- Reef Raider - A fish-like Rahi that is known to inhabit the Pit.
- Rock Lion - A mysterious creature that dwells in the deepest sections of the Archives. Its teeth and claws are extremely sharp and the tendrils of its mane become very hot when the Rahi gets irritated.
- Rock Raptor - A raptor Rahi that traps prey bigger than itself by making landslides.
- Rockworm - A small, venomous subterranean Rahi.
- Ruki - A common fish Rahi. They have powerful jaws and are natural enemies of Tarakava.
- Sand Frog - An irritable frog-like Rahi.
- Sand Screamer - A mysterious creature that inhabited the desert of Voya Nui.
- Sand Snipe - A small biting insect from Po-Metru.
- Sand Tarakava - A relative of the Tarakava that lives in the desert.
- Sea Spider - An amphibious spider Rahi that is the only known predator of the Visorak.
- Shallows Cat - A panther-like Rahi that lived on Daxia.
- Shore Turtle - A flying turtle Rahi that lived in Le-Wahi.
- Silver Chute Spider - A spider Rahi that is believed to be related to the Visorak. They would hunt in the Metru Nui Chute System, catching their prey in paralyzing webbing.
- Slime-Worm - Clawed Rahi about which very little is known.
- Smoke Hawk - A bird Rahi native to Xia.
- Spider Crab - A Rahi that the Barraki used in battle.
- Spiny Stone Ape - A Po-Metru ape that lives in the shadows of the sculptures. When threatened, they curl into a huge spiky ball and attempt to crush their enemies.
- Spine Slug - A parasitic slug that attaches itself onto Skakdi and feeds on their anger.
- Stinger Whale - A large whale-like Rahi.
- Stone Rat - Rat Rahi that once dwelt in the Archives. They can and will eat almost any object, due to teeth that can grind through stone.
- Stone Snake - A Rahi which Krahka once transformed into.
- Swamp Stalker - A reptilian Rahi that lived in the Swamp of Secrets.
- Subterranean Worm - Giant, tentacled creatures that dwelt deep in Onu-Wahi and are spoken mainly in legends, and occasionally spotted by miners.
- Tahtorak - A massive forty-foot-tall Rahi that can speak Matoran. Its species is native to Zakaz and another island south of Metru Nui.
- Takea - A shark Rahi.
- Taku - A small bird Rahi which is a close relative to the Gukko.
- Tarakava - Lizard-like Rahi. Its long forelegs can deliver powerful punches to stun its prey.
- Two-Headed Tarakava - A mutant Tarakava with two heads that was found in Ga-Metru, and then transported to the Onu-Metru Archives.
- Tarakava Nui - The "King of Lizards". Thought to be a mutated Tarakava.
- The Mountain - A Rahi that was once a sentient rock and now has grown into a large Mountain.
- Toa Terrain Crawler - A massive sea beast used by the Toa Mahri.
- Troller - A huge, horned, worm-like beast that lives beneath the Po-Metru sands. Its mouth is large enough to swallow an entire block of the Metru.
- Tunnel Stalker - A gigantic, dangerous, and rare Rahi from Metru Nui.
- Tunneler - A lizard whose body changes depending on what kind of attack it is hit with.
- Ussal Crab - A crab Rahi that can be tamed and used for transportation, mining and sport.
- Vahki Hunters - Rahi that chase Vahki as prey.
- Vako - A great horned rhino Rahi that roams the plains of Po-Wahi.
- Venom Flyer - A flying creature that would travel with the Visorak, assisting them in capturing flying Rahi.
- Visorak - A species of intelligent spider-like creatures whose names mean "stealers of life" in their own tongue, created by Chirox. They can fire Rhotuka spinners with various powers, inject Hordika Venom, and create thick webs. They were led by Roodaka and Sidorak.
- Boggarak - A Visorak breed with a number of water-related abilities.
- Kahgarak - A giant, elite Visorak which can summon the Zivon.
- Keelerak - Wild and unruly, green-colored Visorak.
- Oohnorak - A black Visorak breed with the ability to mimic voices.
- Roporak - A camouflaging breed of Visorak.
- Suukorak - White Visorak able to slow down its life-processes.
- Vohtarak - A constantly aggressive breed of Visorak.
- Waikiru - A walrus-like Rahi.
- Water Wraith - A small marine Rahi disregarded by larger fish. Their outer shells are covered in poison. They were created by Teridax.
- Worm - A small, Kraata-like Rahi that can communicate with others of its species via telepathy. They are small enough to fit into Bohrok headplates designed for Krana, and are able to control Bohrok in the same fashion.