Greenskins are a barbaric and primitive group of races which often band together to invade the lands of more civilised cultures. Particularly strong bastions of Greenskins exist in The Badlands, Dark Lands and The World's Edge Mountains, they are typically seen as an unpredictable menace by the more advanced races of the Warhammer World.
Greenskins are so named for the color of their skin. They are not a single race as such, but a group of distinct green-skinned sub-species who share a few common cultural and physiological traits. Greenskins can be found all over the Warhammer World, but the greatest concentration of them is found in the Dark Lands to the east of the Worlds Edge Mountains and in the area around the Badlands. Greenskin society is tribal, with progress through their social hierarchy by fighting and beating other Greenskins of higher rank. As they rise through the ranks, they grow bigger in strength, size and cunning. Greenskins are universally happiest when they are fighting or in conflict, and if there is no one else around to fight they often squabble (or even have large wars) between themselves. Gork and Mork are the Greenskin gods and sometimes a source of dispute as greenskins have trouble distinguishing one from the other, since they both represent the prized greenskin traits of brutality and cunning. Gork is generally regarded as cunningly brutal and Mork as brutally cunning. The Orcs raise great Effigies to Gork and Mork, often made with Orcish dung.
Due in no small part to their natural aggression and their lack of a governmental system beyond the most basic tribal functions, the Greenskins do not organize themselves into civilised nations but rather into semi-formal groups known as tribes. Each tribe is given a name, though this can often change with the leadership or even if the tribe's leader has a sudden thought, there is a few that stand out. At any given time, and in any given area, the largest, strongest and most cunning Greenskin is followed by the rest, as long as there is fighting to be had. When the mood strikes or a particularly powerful leader wants, many tribes get together and form what is known as a "Waaagh!"; a nearly unstoppable horde of marauding Greenskins that lays waste to anything in their path. Trolls, Giants and herds of ravenous Squiqs are commonly found accompanying the largest Greenskin armies, along with mounted Boarboyz and Goblin wolf riders. When this occurs, otherwise independent tribes will band together to follow the largest and most fierce of them all.
Though they appear universally masculine, Greenkins are genderless creatures. It has never been confirmed by Games Workshop how greenskins reproduce, however early in the history of Warhammer, Citadel Miniatures, the modelling arm of Games Workshop, produced a line of female Orcs. This has since been discontinued and Games Workshop have not mentioned the female Orcs since. However in Warhammer's sister (science fiction) universe Warhammer 40,000, the "Orks" (a futuristic version of the Greenskins), reproduce in the following way:
Orks reproduce through the release of Spores which the Ork's body continually produces, when an Ork dies the spores are released en-mass. In a few hours after the spores hit the ground, they grow into a protective sac underground and a fungi like growth sprouts from the ground that provides the nourishement required. The spores are dispersed by the wind and are very resistant, the only way to ensure a new army is not created is to incinerate the ground for miles around. This is the entire basis of the Orkish ecosystem producing first Squigz, Snotz, Gretchin and finally the Orks themselves. This means the Orks, wherever they go, will have an abundance of food, slaves and other resources, a moving ecosystem that supports them as they go on their Waaaghs! So named because of the color of their waxy skin, the greenskins are savagery personified. They are ill-tempered, primitive, and live only to fight. In the absence of another foe, greenskins will eventually turn on one another for want of violence. In their culture, might makes right and the weakest members of society are one false step away from being dinner.
The greenskins have no homeland to speak of. They capture other race's settlements and then make those places their own, decorating them with tribal graffiti, wood and scrap materials fashioned into crude symbols, and oftentimes, the bones of those they have slain. This leads to a very unique form of architecture that is distinctively ramshackle.
Periodically, a powerful Orc Warboss will unite the greenskin tribes into a single swarming mass called a "Waaagh!", named for the common greenskin battle-cry. In a Waaagh!, the greenskins unite into a stampede of frenzied Orcs, Goblins and Snotlings bent on destroying everything they encounter. Save for pure Chaos itself, there is no force in the Warhammer world as devastating as a Waaagh! set in motion.