Orc

The group of peoples known as "greenskins", or orcs, are viewed by most civilizations as a scourge. In their eyes, the greenskins are nothing more than a horde of murderous warriors that only exist to destroy. This widespread belief is coloured by interactions between the Empire and the fringes of orc society, and has little basis in fact. Nonetheless, collective hatred towards orcs has proved a useful rallying cry for human nations across the ages.
The poor reputation of orcs among other cultures stems from a fundamental divide in their society. Orcs are communal folk, tending to gather in tightly knit tribes that are always on the move. Their tribes are not beholden to any one great lord, but are held together by networks of shifting alliances. Yet a great division sunders their culture. There are two types of orcs, with two very different worldviews. Far more is now known about the peaceful Belaag orcs, thanks to the efforts of imperial scholars in recent years.
The Belaag: Guardians of the Land
The Belaag orcs believe that animal spirits watch over them, and that it is their duty to live in harmony with the land. They tend to flocks of hardy beasts, forage, and move with the turning of the seasons, making the most of their cool surroundings. Belaag orcs are divided into Houses, with many Houses sometimes banding togather to form Great Houses. The Belaag orcs make up the majority of the orcish people, but rarely leave their homeland in Orogrond - their name for the lands north of the Norgannoth mountain range.
The Kharaal: Terrors of the North
The Kharaal orcs are very different. Servants of Mulgarath, an ancient god of ice aligned with a dark power, the Kharaal ride the tundra on wolf steeds, enslaving and pillaging other orcish settlements. A tribe of Kharaal orcs might dominate several tribes of Belaag, extorting resources from them and expanding to include many other Kharaal tribes. After a critical mass is reached, the Kharaal will seek plunder elsewhere - most often in the lands of northern humanity. In exchange for their devotion to Mulgarath, Kharaal orcs are strong, and prone to bloodlust.

Additional Information

Social Structure

Belaag:
Matriarchal society based on ancestor worship; divided into Houses of several hundred related individuals. Clusters of houses band together for support and mutual defense, often contributing resources towards construction of permanent strongholds, which are ruled by a Great House. 
Kharaal:
Patriarchal society based on violent struggle. Individual warbands are led by the strongest warrior. warbands expand through conquest and disintegrate upon death of the leader. Migratory and mobile society, with large enough tribes leaving Orogrond to despoil neighboring countries.

Civilization and Culture

Culture and Cultural Heritage

Belaag society is matriarchal. A warrior woman called an Urskjol, typically with some sort of magical power, rules the orcs. Her handmaidens, called Skjolur, are women of lesser martial ability. The Urskjol and Skjolur make decisions for the house, and raise children in a communal creche.
The most skilled orc warriors are given the opportunity to become a shield-husband of a Skjolur or Urskjol, with multiple Urskjoler typically having a single powerful shield-husband. Children born by these unions are raised in a communal creche by the Skjolar until age 10, at which point the male children are separated and returned to their fathers.
Though not all children are raised by the Skjolar, orc unions in general tend to be polygamous, with multiple powerful women having one husband.

History

Orc history is passed on through oral tradition. Though the orcs have a written language, it is used for practical purposes - lists, accounting, and so on, and so stories are passed on by word of mouth.
The Korkoriad
The Korkoriad is the most well-known tale of the Belaag orcs. It details how an orc shaman named Korkorus freed his people from servitude, as they were held in grasp by Father Winter.
At the end of every winter, Korkorus' village chose a sacrifice to give to Father Winter, a young child, in exchange for Father Winter allowing a brief bit of sunlight and warmth through the clouds to let plants grow. That year, Korkorus' sister was chosen, and despite all his protests, was frozen solid by Father Winter. Out of grief and guilt, Korkorus left his village for the Norgannoth mountains, looking for help. He roamed for years, beseeching the gorak, the rock devils, the frost eels, the mammoths, and the dire wolves for aid, completing a trial for each of them in turn. After five long years, he hatched a plan, aided by the cunning of the dire wolves. The rock devils granted him a huge piece of obsidian, and with the help of the frost eels he turned the obsidian as transparent as ice. With the mammoth's strength, he broke the hunk obsidian into a flat shard. Finally, with the antlers of the gorak, he polished the clear obsidian to be as smooth as a clear lake. When Korkorus returned to his village at the eve of winter's ending, he channeled the light of the setting sun into a radiant beam that burned Father Winter to cinders. From that day on, the orcs were free from winter's tyrannical grasp, and they worshipped only the wise creatures of the land.
The Korkoriad is an epic poem that can take up to 12 hours to recite in its entirety, though it differs from house to house.

Human Knowledge of Orcs
For many centuries, human knowledge of orcs was limited and extremely biased:

"The race of Greenskins is a savage collection of barbarians, ranging from stunted thralls to hulking orc warlords. Eking out an existence in the northern steppe, the orcs align themselves with all manner of horrible beasts and exist only to serve their malevolent god, Mulgarath, a being of ice and blood who demands constant bloodshed from his followers. Since the orcs make nothing themselves, they rely on raiding the noble holds of the dwarves and the towns of humanity for slaves and plunder. To be a captive of an orc warband is a truly miserable existence, at best being being forced to construct petty hovels and toil for decades before dying of starvation, at worst being tortured and eaten alive."

"It is a well known fact that orcs can interbreed with Humans, Dwarves, and Elves. The first generation of such a union, a half-orc, is much more intelligent and civilized-looking than a true orc but is still generally an outcast in most cultures. Half-orcs may serve as workers, auxiliary troops, or mercenaries in more brutal regions. The product of a union between a half-orc and another race forms a tough but slightly deformed person that can sometimes pass as a human. These quarter-orcs, typically still referred to as “half-orcs” for the sake of simplicity, are fairly common in the Northern reaches of the Empire, which have been long subject to Greenskin incursion."

Note: Some Valmer scholars believe that Greenskins originated from cursed, twisted humans. I have not found any evidence to corroborate this.
Brother Aelwald of Thorn,
A Treatise on the Greenskin, 356 HR
Yet in recent years, human knowledge of orcs has improved, driven by Emperor Karl's funding of scholarship. Some orcs have even become imperial citizens, much to the horror of traditional Holmgardians.

Lifespan

60 years

Average Height

5-7 feet