Orcs

Ruled over by savage shamans, the savage hordes of the orcs and their goblin cousins ride out from their wasteland homes to take what they need from lesser races. The sound of their elf-skin wardrums blending with the howls of the orcish wolf riders, and the chitinous scrapings of the goblin-controlled spiders, to create a discordant song that has come to be feared in all civilized lands.
No one is entirely sure what primordial rock the Orcs crawled out from under so long ago. One thing everyone can agree on is that you don't really want them near you. At best, they tend to drive down the property value of the neighborhood. At worst, they burn down the neighborhood.

Orcs believe that they are the rightful inheritors of all things green, and that they have the right to take away anything belonging to non-green beings. In other words, the entire planet. Fortunately, most Orcs tend to suffer from an attention deficit disorder when considering anything not related to slaughtering other races. This alone has prevented them from expanding in any serious sense beyond the borders of Orgark, the Orcish homeland.
Though Orcs aren't known for their social skills, they excel as shock troops on the battlefield. Notoriously resistant to pain, an Orc may keep on fighting until it can simply no longer move.
Occasionally, an Orc may be a bit more savvy than his fellows, and show promise as a leader. These warlords come to realize that not all power is physical. Being a warlord means keeping a constant eye on those other Orcs who fancy themselves as leaders, and are willing to backstab to get there. The trick is to get them to focus on something else like constant raids into civilized lands, quests into unknown territory, or just a good old-fashioned Goblin-stomping party. Of course, if it comes down to it, the warlord may have to defend his title by brutalizing the upstart Orc in the most vicious and public manner possible, for all to see. Just so no one else gets any ideas about who's in charge.
The God Rock

The Screaming Moon Shamans claim that a long time ago, before any other races appeared, the great-green-god-Grezz spewed forth a mass of perfect beings. (Elven scholars have debated the correct translation of the Orcish word for "spew" and have come to the conclusion that it's best just left alone.) This new race was the Orcs, and the world was theirs. Later, other gods gave rise to their own races who tried to take the land from the Orcs.
The Shamans say that to assist his children in their struggle for dominance, Grezz "dropped" the God Rock. (Once again, direct translation of "dropped" has been problematic and has led many researchers to speculate that Grezz may have been the most incontinent of the gods.) Once the Orcs realized that the mountainous rock was loaded with strange ores, they began mining it for weapon materials. Most Orc combat gear is, at best, shoddy replicas of other races equipment. The ethereal metals of the God Rock gave the Broken Tusk weaponsmiths something new to experiment with.
This also resulted in the Goblins moving into the Nightshade Forest and Ferox Swamps, as the larger Orcs insisted on bullying them into mining the God Rock. Changing their tactics, the Orcs offered the Goblins a small share of the God Rock's ore in return for continued excavation.
Urkgar
Urkgar can arguably be claimed as the Orc capital. It's rather a place where they gather to sharpen their weapons and plot world domination. The buildings and crude trades that sprang up in the area are more of an afterthought than the result of any rational planning.
There are other Orc settlements scattered throughout Orgark, but none rival Urkgar in size and random acts of violence. Urkgar is where Orcs go when they feel the need to come together and kill...which is most of the time.
The ramshackle city of mud huts and patchwork buildings teems with green-skinned life. The raggedy bazaar offers everything from foods best left to the imagination to exotic herbs and materials brought by Goblin merchants from the south.
The self-proclaimed ruler of Urkgar is a huge Orc known as Big Garg. Seen by most Orcs as the baddest green-skin to tread the face of the world, Garg has attracted a huge bodyguard of minions to do his bidding. Garg acts as the closest thing to a warlord/mayor that the cities has. His word is law, which doesn't really stop the daily chaos and destruction that ensues, because most of his words deal with killing, breaking, stomping, etc.
Grugrak smirked cruelly as he looked down into the valley. Surrounded by his Orcish lieutenants, he surveyed the forces of Knights assembled on the field below. Behind him, the massed Orc horde murmured and growled impatiently.
He pointed down the slope to the verdant farmsteads and forests swarming with Imperial forces.
"There, now," Grugrak rasped to his war leaders. "Yer see that?"
"Yeh," one of them replied cautiously.
"What do yer see?" Grugrak fixed the Orc with a madly staring eye.
"Uh...stinkin' Umans!"
"What else?"
"Er...fluffy sheep?"
"Wrong!" Grugrak smacked the back of the Orc's head with an armored gauntlet. He pointed back down the valley. "It's green. All of it. Trees, grass, the hills. It's all green. And wot are we?"
"Orcs!" Another one roared.
"We's green!" Grugrak spat back. "That means it was all made fer us! By rights, it's all ours!"
"Yeah!" A chorus of harsh Orc voices filled the air.
"So we's gonna go down there and take it!" Grugrak raised his fist into the air. The Orc horde stirred to life, roaring and charging down the hill toward the Knights. Grugrak grinned to himself as he plunged along with the horde. "By the end of the day, lads, we'll be dancing in the Uman's guts!"