Beyond Humanity, the Skrell, Unathi, and Tajaran who make up their space-faring neighbors, the Skrellian clients the Teshari and Dionaea, and the positronic brains and Prometheans invented by humans, there are a vast number of other species who, for one reason or another, are not found in human space at large.
Probably the best known of these aliens are the Vox, a bird-like species with a very rough comprehension of Galactic Common and an even looser understanding of property rights. Vox raiders have plagued human merchants for centuries, and Skrell for even longer, but remain poorly understood. They have no desire to partake in diplomacy or trade with the rest of the galaxy, or even to conquer planets and stations to live in. They breathe phoron and appear to be well adapted to their role as space-faring raiders, leading many to speculate that they're heavily bioengineered, an assumption which is at odds with their ramshackle technological level.
The Singularitarians were a massive, highly-advanced spacefaring race which are now believed to be extinct. At their height, they extended throughout all of known human space, with major population centers in the Precursor's Crypt region, as well as significant swaths of Skrell space, until they were wiped out by a self-replicating nanobot plague that still coats their ruins as a fine layer of dust. They left behind the proto-positronics, as well as several high-yield phoron deposits and other artifacts of technology studied, cautiously, by the races that survived them.
Very little is known about the biology and physiology of the Singularitarians, who are believed to have been largely post-biological. The Vox claim to be the race that created the positronics, but said claim is only ever brought up when they claim the right to take any positronic they want. Some more open-minded xenoarcheologists have voiced the opinion that there is some truth in their claims, but it's far from a scientific consensus.
The Uehshad have a tribal society deep in the oceans of the human rimworld of Ukupanipo. Because they exist in high-pressure, low-temperature, saline environments, they cannot share living space with the rest of galactic civilization or proceed down a familiar path of technological development. In 2574 CE, most Uehshad hunt large fish-analogues with spears of shell and bone, and build temporary structures out of thatch made of a tall, woody water plant. A few tribes in some of the more rich regions of the planet have begun adopting seasonal agriculture, a development regarded with great anticipation by xenobiologists.
They are partially humanoid, with bulbous eyes, thick throat sacs used for echolocation and communication, two stubby grabbers with four-fingered hands and four long tentacles. They live in tribal social groups called pods with high levels of endogamy and territorialism.
Some Uehshad tribes have been contacted by xeno-anthropologists, usually positronics in pressure-resistant specialist shells. SolGov has stated opposition to technological uplift of the Uehshad, and generally enforce a quarantine of the system. However, during the SolGov-Hegemony war, a daring group of Ue-Katish pirates airlifted an entire pod out of Ukupanipo and brought them across the border to Qerr'balak, where despite sapient rights protests they remain in specially prepared aquariums.
The most advanced pre-FTL species encountered by humanity, the Khepri are a race of eusocial insect colonies with a late industrial level of technological development, discovered on the hot, water-poor planet of New Cairo. The average Khepri is warlike and hostile to outsiders, making contact difficult and convincing the international community to refrain from technologically uplifting them.
Each Khepri "individual" is actually a colony of about ten thousand bright blue beetle-like insects, each one with four body segments and eight legs. The Queen of a given colony is an order of magnitude bigger than the rest of the individuals, her huge swollen thorax covered in pheromone trails. Sapience doesn't reside in the Queen or any other individual in the colony, being instead an emergeant property of the colony's complex dances and pheromone marking.
At present, the Khepri have formed nation-states, built large, industrialized city-mounds, and are engaged in vicious warfare using artillery, suicide bombers, and drone-to-drone combat. Most contact with xenos have ended badly for them, with a mound of Khepri famously killing and eating a pair of Unitarian missionaries who attempted to make contact. The one race exempt from this is the Dionaea, who have formed tenuous diplomatic relationships with them. Only one Khepri colony exists off-world, living in a Dionaea gestalt in orbit above New Cairo and acting as a diplomat to the rest of the galactic community.
|Outdated - The lore here may be partially or wholly outdated. Do not rely on it.|
The Vret are an Unathi client race. Unlike the Teshari and the positronics, Vret are not permitted to leave a small region in the core of Hegemony space except under specific circumstances-- none are believed to have crossed the border into SolGov, Skrell space, or Natuna. They evolved on a small moon with a thin atmosphere and find standard temperature, pressure, and gravity to be somewhere between agonizing and painful.
They are very tall, with long limbs and frail bones. Their overall body plan is somewhat humanoid, but they have an additional pair of arms with graspers used to secure handholds in their native environment located on their midsection, very large ears, and blue blood. They speak a low, harmonic language very difficult for species without the Vret's sensitive hearing to pick up on. Upon their discovery by the Unathi, they had explored their co-orbiting moons and sent probes to the world they orbited-- but lacked the industrial capacity or technology to resist Unathi subjugation.
Due to their biology, the Vret rather naturally segregate away from the hardier Unathi, and a majority of Vret off their homeworld live in orbital habitats as life-sustaining moons are very rare. In Unathi media, they are stereotyped as clumsy and timid servants. The ease of conquest of the Vret contributed to Unathi overconfidence during the SolGov-Hegemony War, and the Fourth Great Reformation of the Unity has given the Vret hope that restrictions on their species will be lifted in the near future.
A spiderlike species on the far side of Moghes from Sol, humans know very little about the Schierans. They are believed to be directed by Queens, but not to be gestalt consciousnesses like the Khepri and Dionaea. It is known that the Unathi have been in conflict with them for several decades, but not what form that conflict takes.
The average Unathi knows quite a bit more than the average human. Schierans retain the compound eyes, chitin plating, and strange physiology of insects, but possess enough internal structure to stand upright in high gravity and to support a dense, energy-hungry brain. Only Schieren Queens have a fully-developed brain, with drones being mindless servants with the intelligence of a clever dog. Previous a fractious, warring race, the Queens banded together when the Unathi attempted to invade their homeworld, and have spread throughout the stars, constructing new colonies faster than any other race (save, perhaps, the Skrell) could and quickly becoming a serious threat to Unathi border worlds. The ensuing conflict helped divide Hegemony attention during the war and, possibly, lead to its resolution in humanity's favor.
The Qyga are a tribal civilization, a bit more advanced than the Uehshad, that live in a boggy garden world in between SolGov and the Qerr Monarchies. The exact location of the world is a carefully guarded secret by SolGov officials who fear Skrellian intervention in the development of the Qyga.
Qyga have discovered fire and agriculture, and are believed to be on the verge of a cultural explosion similar to the birth of civilization in Mesopotamia. They live in bands of around 200 individuals in rich mud bogs and are currently suffering from a very low population, similar to humanity after the Toba population bottleneck. There are already concerns that contact with human research expeditions, even very indirectly, will influence their development unnecessarily. Some, though, point out that most species already have some level of belief in ancient aliens.