Humans
Humanity is separated into three notable cultures, each having vastly different views and societies:
The Imperium of Man: Until recently, the most powerful and stable of the Human cultures, the Imperium is a strict totalitarian state, guided by the teachings of their Church and the guidance of their divine ruler, the Empress of Man. The people of the Imperium have embraced the practice of mechanical augmentation and are know to be the experts in cybernetics in the galaxy.
The Fringers: Originally formed when humans fled the confining strictures of the Imperium, this loose conglomeration of free peoples have found a way to thrive on the harshest of the galaxies planets'. The Fringe has become the de facto home of the recent influx of mutants in the galaxy.
The Meurlain: A separate offshoot of humanity, the Meurlain are the preeminent masters of pursuits of the mind. Their society embraces science and mathematics and the philosophies of logic. As such, they have become the most knowledgeable race in the galaxy regarding psionics and gate travel.
The Tribes
The non-humans of the galaxy are collectively known as the tribes. The only thing truly tying them together, aside from their non-human status, is a common religion.
Aeshma: An Aeshma is actually a collective of individual organisms unified to make what would appear to be one single being. This leads to their communistic views, but does not explain their aggressive warrior natures.
Dahhak: The horned Dahhak are most known for their persuasive nature and their trafficking in slaves.
Kshathra: The silicon-based Kshathra were enslaved by the Dahhak until 200 years ago, when they rebelled and took the Dahhak homeworld as their own.
Midir: The insectoid Midir are an unusual race whose culture is almost solely devoted to corporate mercantilism. Their Hive Mind makes them more alien to the other races than any other, but allows them to excel in their pursuits.
Nasu: The Nasu are symbiotic creatures that inhabit the recently dead and bond to those bodies to better function in humanoid societies. While they make many uncomfortable, their natural aptitude towards the healing arts make them invaluable to others.
Yazatas: The Yazatas are paradox: a plant-based life form with an undeniable bond to nature, but with a technological aptitude that makes them a power in the galaxy.