Humans are not the only intelligent species in Abraxas. There are others, some of them well organized and genocidally hostile. The eventual ascendency of Man is not a foregone conclusion.
An intelligent pre-human Terran race descended from pterodactyline ocean gliders. When the vlis's distant ancestor adapted to life on the ground, the powerful forelimbs evolved into its legs and the smaller hind limbs became its arms. Several hundred million years on, the hind limbs moved around through a widening of the pelvic girdle and the legs moved back. The creature thus has a low hunched stance with the thorax and head supported like a table-lamp on strong backward-jointed legs; the overall height is about five feet.
Possessions are typically carried in a pan or bag strapped under the thorax; the vlis's long slender-digited arms can easily undo the flaps, remove a needed item, and reseal it with horridly unhuman dexterity. Sometimes this pan will be found to contain a freshly-severed human head; the vlis are believed to collect such heads in order to restore them to sentience in their laboratories, where the head can be maintained in a vat indefinitely while the vlis subject it to interrogation and experiment.
The vlis are man's deadly rivals on Earth, regarding humanity as usurpers of their rightful supremacy. In addition to being skilled fighters, usually with a spear held in both hands, the vlis can use magic and have a sonic screech attack which can distract or stun an opponent.
Creatures from a star cluster beyond the Coal Sack, who came to Earth by psychically broadcasting themselves through outer space to escape their own dying world.
Ulembi have large heads whose hard ridged integument resembles a walnut. This skull protects the creature's huge brain. A ring of dark globular eyes protected by deep recesses allow the ulembi to see in all directions at once. There is a short neck and then the ulembi's trunk bifurcates, the two stout limbs resembling large serpents. At the end, each limb divides into four tentacular fingers. The ulembi can balance on one limb or on its "elbows" while holding something in the fingers, but rarely needs to do so because all ulembi are able to manipulate small objects by telekinesis.
When fully reared up on its limbs, an adult ulembi's head can be as high as eight feet off the ground. But it can also splay its limbs out low, moving with ghastly stealth through undergrowth no more than a few feet high.
In combat the ulembi is able to bristle its scales, giving the limbs a rough jagged surface like pineapple skin. This allows it to flay the skin off an unarmored opponent. Young adults sometimes wear bronze vambraces on the lower limbs, with which they can deliver powerful whip-like blows. Older ulembi disdain physical combat altogether, preferring to use their psionic power to instill a feeling of dread and despair in a foe.
Given a short time with a subdued victim, the most powerful adepts of the ulembi can psionically rewire his brain so that he will serve as their agent. This can even take the form of subliminal commands, so that the victim does not know he has been affected. Eventually tumors form in the brain of the victim, however, and madness and death soon follow.
The offshoot of humans altered by an ancient wizard's genetic sorcery. Eremen are recognizably human in origin but have the features required for survival in the desert: large membranous ears, heavy brows, a limber frame, folds of fat around the belly, and elongated webbed digits. A dorsal fin that usually lies flat along the spine can be erected for temperature control as well as conflict and mating displays.
The genetic changes have caused some reduction in these creatures' intelligence: you might be attacked by one wielding a metal club it had found, the club actually turning out to be an ion pistol that it lacked the wits to operate.
Hive-dwellers, the descendents of an alien race stranded on Earth in the far past. The churuk thrive best in the sulfurous atmosphere of volcanic rifts, but are hardy enough to tolerate normal air for days or weeks at a time.
The basic body form of a churuk is of a lozenge-shaped torso armored in chitin and with three limbs arranged around the rim. This form can develop in quite different ways, however, according to chemical jellies administered to the eggs during development. Some churuk hatch as Brains, others as Workers, others as Striders. The Striders have powerful legs. The Workers have one of their limbs developed massively for heavy labor or combat; for travel they can move slowly with their other limbs or latch onto the back of a Walker. The Brains are the most intelligent; they have only limited mobility but can latch into the back of a Strider or Worker and directly take charge of its cerebral ganglion (its eyes then close in sleep).
Mottling on the chitinous shell allows a churuk to identify the members of its hive and egg-clutch.