A few years back, I started work on a RPG idea I had, set in around 2470.In addition to three Human societies (A Corporate Plutocracy, a Constitutional Tyranny, and an Aligned group of Anarchies called the Freeholds), I had the following alien races.
The Ral-Asha: Essentially, my universe's Klingons, (Worf and Martok, not Gowron.) A warrior race of felinoid centaurs - having six limbs, four legs and two arms. 420 worlds, 720 billion inhabitants. A Hereditary Monarchy with a Feudal subculture. Ruled by an Emperor with 5 Dukes and 420 planetary governors. Organized in to paternally-centered Prides, and societal standing is based on a complex system of family standing, personal honor, and combat experience.
Military service is obligatory for four years after a Ral reaches 10 years of age.
The Korin: Ever meet an insectoid Samurai? Bipedial, with tough exoskeletons and luminous antennae, these aliens have managed to perfectly blend the way of the warrior with an astounding amount of calm religion. NOT someone to be provoked. "More calm under fire than a battle android," has been said of them. 440 worlds, 800 billion Korin. Military/Religious Oligarchy, ruled by an emperor, 4 Battlelords, 44 Sector commanders, and 440 Generals. Social standing is determined by birth order, family, prowess in combat, and distance along the Korin "Design," a religious path not discussed with outsiders.
The Banfochon: Evolve a Trilobite for a billion years, and make him both stupid AND unpleasant. That's a Banfo. My universe's real baddies. Xenophobic in the extreme, their stated intent is to wipe out all other life. Highly expansionist. Heavily armored semi-arachnids with compound eyes and numerous walking and manipulating limbs. 590 worlds, crammed with 6 trillion inhabitants (did I mention they breed fast?) Military Absolute Dictatorship, ruled by a "God-Emperor", 10 Masters of Invasion, 59 Overlords, and 590 Planetary Overseers. Social standing appears to be determined by opponents killed and property owned/siezed.
The Kel: A 7-foot, 400 lb, telepathic slug. Need I say more? The Kel are all telepathic and telekinetic, having powers which can vary in range (by individual) from a few yards to tens of thousands of miles (for a few highly gifted ones). They can read minds, and a very few trained ones can influence thought patterns. They enjoy games, riddling, logic puzzles, and mimicing and studying other species' idiosyncrasies. They need synthesizers to speak to non-telepaths. 320 worlds, with 640 billion inhabitants, governed by a Full Democracy in which all mature individuals participate telepathically, led by a President and 320 High Committee members. Social standing is based on riddling and logic ability, artistic achievement (creating greater puzzles and designs), and contributions to the group experience.
The Tak: The Mystery Guys of my universe. Nobody knows much about them. 1.5 meters tall, pale blue with slightly pudgy limbs, long fingers and oversized heads, large dark eyes, and a jaw structure which makes it look as if the Tak is constantly smiling a wide, close-lipped smile. They have been likened to "little blue munchkins with jack'olantern heads." The Tak are elusive, and their ships seem to use organic technology. Tak never speak to each other, they simply nod, though the Kel claim they are telepathically unreadable. They DO speak to other races, though. Ships challenging Tak vessels have been known to suddenly lose all power, or find themselves chasing shadows. No Tak vessel has ever been known to engage another race's ships in combat.
The Star League: A quasi-Federation created by a few smaller races, banded together in the wake of Banfochon attacks. The 5 most important races are:
The Meredii: Reptilian humanoids. Administrators, artists, and educators.
The Belthari: Agile lemurlike primates with highly dextrous fingers and two thumbs. Renowned technicians and mathematicians.
The Cantela: Squidlike ceatures that must travel in enclosed aquatic environments or specially designed exo-suits. Navigators, with an innate understanding of language and spatial dynamics.
Vortoo: Six-limbed Avians (including functional wings). Very light, but strong. Extremely keen vision. An adventurous race when compared to the others, despite a lower general level of technology. Often become scouts, explorers, and sentries.
N'gusat: Evolved from grazing herbivores. Very docile in nature. Six-limbed and centaurian. Masters of agriculture and nutrition, doctors, biologists.
------------------
"We shall not yield to you, nor to any man." -- Freak, The Mighty.