Peacekeepers: A militaristic group of Sebaceans. Other cultures hire them to keep order but once they get a hold on a society, they take over. They’re xenophobic and condemn as irreversibly contaminated anyone who has more than a passing contact with unclassified species. Centuries ago, the Eidelons took a species from a planet (probably earth) at the edge of the galaxy and assisted in their evolution, Which explains why the Peacekeepers are so much like humans.

Peligrinos (Mention Only): Dregon Casanova invited Aeryn to take a trip to the barren lands outside the city to watch the Peligrinos migrate. Look at the Princess, Part 2

Pilots: A species of large crustacean-like beings who are unable to travel the stars on their own, they must be bonded to a Leviathan. This bond is symbiotic and for life. Pilots are "most fulfilled when serving others" and enjoy having passengers aboard their ships. The Pilot acts as the Leviathan's control center, while the Leviathan provides nutrition to the Pilot. 

Plokavians: Weapons designers and dealers. They’ve designed several of the nastiest weapons in the Uncharted Territories including Novatron gas, shatter grenades and seismic disrupters. Dispersal is their method of choice for capital punishment. They aren’t the prettiest species we’ve run into – they look like they’re covered with melting wax and continually ooze…something that drips and hisses when it lands. The Ugly Truth

Prahtikrah (Mention Only): The shipbuilding folks who installed the Leviathan bait on a Siren Star to lure them to their death. Fewer Leviathans meant more ship sales, resulting in a larger fortune for the Prahtikrah. Meltdown

Qatal Mollusks: A clam-like organism which should be eaten by only one person. When its halves are eaten by more than one person, the mollusk's bacteria transmit to the other half, and each person feels what the other does. The end result of this type of food poisoning is fatal. Coup by Clam

Qujagans: This species seems to be related to Eidelons. Both live on the water planet and both have faces that split open for various reasons. It was a Qujagan who turned Crichton & Aeryn into crystals so they could be analyzed. Bad Timing

Ravorc: This being starts out as a vorc, a meek little parasite hunter. Once it senses a parasite it turns inside out and becomes the predatory ravorc. When in ravorc mode, it attacks the parasite and kills it. At least that's how it's supposed to work. Chiana brought the vorc on board Moya to help them with a parasite that came aboard in some supplies. Beware of Dog

Relgarians: A peaceful race that enjoys deep-space explorations, especially aboard Leviathans. Linfer, a Relgarian and one of Scorpius’s wormhole researchers, defected from the Peacekeepers and came to Moya, offering Crichton the solution to wormhole technology in exchange for Moya. John refused but Pilot and Moya were tempted. Losing Time; Incubator

Scarrans: A somewhat horsy-faced, heat loving species. They have an extremely tough skin, impervious even to a pulse blast. They’re rivals of the Peacekeepers for territory and technology. They have some kind of a built-in truth serum effect on people and their hot breath can be lethal. Their heat gland is located in their upper torso and when it’s removed, it weakens them. The ruling class aren't as horsey or as well-armored as the "regular" Scarrans. Look at the Princess, Parts 1, 2, and 3; Won’t Get Fooled Again; Season of Death; Incubator; Infinite Possibilities, Part One: Daedalus Demands; Infinite Possibilities, Part Two, Icarus Abides; Fractures; I Shrink, Therefore I Am; Bringing Home the Beacon; Prayer through Peacekeeper Wars

Scorvians: We’ve never seen a Scorvian in it’s natural state, only one who was genetically altered to look like an Ilanic. They’re presently at war with the Ilanics. One of their combat moves is a neural stroke which renders the victim unconscious. Back and Back and Back to the Future

Sebaceans: A race that resembles humans but with several differences. For one thing, they live a lot longer than humans, well over 100 years. They’re intolerant of heat and go into a state called heat delirium, which eventually results in what they call the living death, a state similar to a coma or Alzheimer’s disease in humans. They have a paraphoral nerve that is responsible for filtering waste from the body in much the same way as a human liver. The paraphoral nerve can’t regenerate when damaged and only a tissue transplant from a compatible donor can save the injured Sebacean. Recently an artificial transplant has been developed. Peacekeepers are Sebacean, but not all Sebaceans are Peacekeepers.

Sgabba Flies: E'Alet made these little bugs inside his head. Once someone is bitten by a sgabba fly they become susceptible to suggestion. Then E'Alet uses his mental powers to induce them to kill. Aeryn was bitten and she killed seventeen people without having a clue why she did it. Or even that she had done it at all. A Prefect Murder

Shakloom: A huge lobster-like species. It’s a source of food on the planet Acquara. Jeremiah Crichton

Sheyangs: A fire-breathing fishy looking species. According to Aeryn, they’re scavengers and cowards. A ship full of Sheyangs looted the Zelbinion of nearly everything useful except a defense shield.  PK Tech Girl, Liars, Guns, and Money, Parts 2 and 3

Sintar (Mention Only): A creature who can sometimes turn spirits corporeal. Or not. Aeryn’s “father” encouraged her to believe in this creature and not to lose hope. The Choice

Skreeth (Amy Salas): A species with a really bad attitude and the ability to send their thoughts great distances. Commandant Grayza employed one to find Crichton via his DNA. The thing ended up on earth, killing DK and his wife. It was harder to kill than Rasputin, surviving several gunshots, pulse weapon blasts, and electrocution with a chandelier before D'Argo killed it with his ship's main weapon. Kansas; Terra Firma

Stykira: Certain members of the Bank Slave race who are attuned to the dying. Stark is a Stakira and Scorpius tortured him over and over in the Aurora chair trying to learn his secrets. The Stakira have the ability to cloud their thoughts and thus Stark was able to hide what Scorpy wanted. The Hidden Memory, Liars, Guns, and Money Part 2; Peacekeeper Wars

Strannat: A crab-like creature that senses brainwave patterns and is extremely sensitive to cognitive dissonance (tension due to mental conflict). It can tell if a person is lying and will then kill the liar. The Sovereign of Kanvia had one in his office living in a container that looked like a fish tank. Thanks for Sharing

Sykarians: They never aspired to travel in space. Until the Peacekeepers came, they lived on a garden planet but the tannot root is now all they grow. Rygel’s explosive body fluids convinced them that the Peacekeepers were using the tannot for weapons and not food. When the crew returned to Moya, the Sykarians were talking revolution. Thank God It’s Friday, Again