Bandits - Bands of criminals, robbers, highwaymen, and so forth. Although they live an outlaw life, and may dress the part, bandits can and often do interact with "civilized" society. They may sell their loot to a rich merchant; they may buy supplies from a sympathetic settlement; many bandits have a woman and children in a settlement that they support with their ill gotten gains. Bandits are generally neutral or evil, being motivated by selfishness or necessity, although there are examples of lawful bandits (partisans) and even good-aligned bandits (Rocket Robin Hood). Excessively evil bandit-types, especially those of chaotic evil alignment, generally fall under the category of Raiders. Bandits are generally 0-level fighting men equipped with leather armor (in order to facilitate speedy getaways), although mounted bandits may wear mail as long as it doesn't unduly slow their steed. There may also be several 1st-level thieves in a gang of bandits.
Cultists - Religious fanatics that keep their faith and their practices secret, usually by masquerading as some other type of Man or operating far, far away from civilization and any prying eyes. They are usually based out of a stronghold, but nomadic bands of cultists do exist. Cultists are generally neutral, evil or chaotic. Lawful and good Cultists are usually some sort of secret society performing some protective function; therefore they are very, very rare in the venal, grasping, decadent world of Planet Algol. Their leaders are almost always some variety of Sorcerer, Sage or Mind Wizard, although Assassins are far from unknown in that role.
Raiders - Bands of murderers that thrive on slaughter, destruction, and rapine. Prone to cannibalism, foulness, and acts of a bestial nature. Many practice scarification and they are generally clad in ugly, harsh, filthy garb and grisly trophies, although some drape themselves in garish, outrageous finery instead of the former or as well. Almost always chaotic evil in alignment, many are demon worshipers or worse. Raiders are differentiated from Bandits by the viciousness and foulness of their actions; Bandits prefer letting their prey go free in order to rob them later, Raiders prefer the ecstasy that slaughter brings them. Raiders often consort with evil nonhumans, usually as either allies or servants.
Savages - Hunter-gatherers of low (generally stone-age) technological prowess with a tribal society. The character and culture of different tribes of savages can vary wildly. One savage tribe could be chaotic cave-dwelling wretches that feed on raw vermin, attack with jagged rocks, and do not possess fire; another could be a lawful sophisticated, society of artistically talented cannibals with a rich culture. Savages are generally unarmored and usually attack with clubs and spears, although this can vary wildly as well. Due to their rigorous environment savages usually fight as 1 hit die monsters instead of 0-level humans.
Zealots - Warrior fraternities of religious fanatics, usually dedicated to the Lords of Light as chaotic fanatics are usually Cultists or Raiders, although exceptions do occur. Zealots usually live in nomadic bands or dwell in a temples or monasteries, although some serve as followers for particularly religious powerful lords and the type. Zealots are typically either draped in garish devotional ornaments or clad in severe, simple garb depending on the inclinations of the particular sect.