Beastmen
Where the Warriors are Chaos tanks and Daemons are Chaos cheese, the Beastmen are the true Chaos horde. The Beastmen call themselves the children of Chaos, descended from outcast mutants hurled into the cursed woods of the Drakwald. They are considered a mere nuisance by the Empire and the Bretonnians, but the Wood Elves know how dangerous they truly are. The favorite activities of most Beastmen include toppling waystones, erecting herdstones, kidnapping/raping/eating humans, and, of course, plain old smashing shit! They hate absolutely anything built or anything that is pure and make it a priority to destroy and defile that which the civilized races cherish. In short, they're a bunch of drunken anarchist fucktards that hang out in the woods, surfacing only to pillage and defile - which is actually kinda awesome if you're into that sort of thing!
Print History
The Beastmen weren't always "the Beastmen" as we know them today. For the longest time, they were actually part of a unified chaos army, but due to the fact that people seemed to like to roll with either all beast, mortal or daemon army lists, Games Workshop in their infinite wisdom decided to gradually split off the armies. Despite getting splitoff into an army of their own, they still always play second fiddle to every other villainous faction in the setting.
Beasts in Hordes of Chaos
Way back when, they were chaff; they were squishier and quicker than other mortal units and they were good at setting up charges, which daemons couldn't really do. There were also a couple of special and rare units that were "beastly," but nothing much.
Beasts of Chaos
They were pretty bad in this edition, essentially being the bitch of Chaos. Indeed, they had almost no redeeming qualities of their own. This is because, when they were first split from the Hordes of Chaos, they were nothing more than an unruly band of meat shields. In fact, because they could move faster, it was preferable to field a few beast packs to soak up arrow fire and act as distractions while fast-moving daemons got the flanks and warriors hammered the front ranks.
This does not make a competent, full army.
They had core units that mixed low Toughness and low Leadership; they basically got lightly armoured Ungors with spears and tough, brawny brawlers in the form of Gors, alongside skirmishers that could scout. The only real tactic was to lineup Gors in the front and Ungors in the back, jabbing with their spears. The only alternative was to supplement with Warhounds (who can't take a hit) or take a bunch of tough, strong Bestigors (who were overpriced and much slower than everybody else).
The only interesting thing about the Beasts was that they had access to a lot of cool special and rare choices, like Chaos Trolls and Ogres, Dragon Ogres and Shaggoths, etc. However, Hordes of Chaos had better shit and later on, the Warriors of Chaos would absorb almost all of the Beasts' specials and rares.
Beastmen
Sometimes referred to as "the WEAK chaos army," it more or less resembles a normal horde style army in Warhammer Fantasy Battle with cheap, expendable troops, average leaderships and little immunity to psychology. The things they otherwise don't have are anything resembling armor or any kind relevant shooting, but they make up for it with Primal Fury which gives them hatred on a passed leadership test each round of combat on many of their units. The Herdstone magic item allows Beastmen wizards to score extra power dice for their spells, allowing Beastmen to pull off a lot of spell support to augment the cheap and reliable core units. They also excel in cheap chaff and redirectors in the form of Ungor Raiders, Razorgors, and Harpies, and fielding fairly costed chariots in core. The biggest change was the totally unnecessary nerf to Ambush - which is best explained in the tactica (see below).
The Beastmen today are fair, if weak as a stand-alone army featuring decent core choices that can win through the support of augmentation and hex spells, and colorful selections of heavy hitters like the (overpriced) Ghorgon and the (totally underused) Doombull.
Real world Inspiration
The standard way of creating a fantasy race or culture is to take one real world culture and base everything off of that. The Empire is 30 year war Germany, Bretonnia is Medieval French fused with English Arthurian myth giving them a strong British feel as well. Dwarfs and Elves have their own sort of base line culture based on Tolkien and with a large part of Warhammer fantasy in it nowadays as well.
The Beastmen, however, are based on the popular conception of the barbarians who tore Rome down. First they have no interest other then smashing civilization apart for the sake of smashing it apart. They have in their back ground that they pay homage to large 'herd stones' which are similar to the Celtic shrines (think Stonehenge). Lastly, they are Beastmen and satyrs are associated with paganism. Ever wonder why the Devil has cloven legs? Early Christians used the old greek god Pan's (the original satyr), as the devil because he was a god of sex (and shepherds) and Christians are, lets not beat around the bush, against recreational sex outside marriage (due to the Bible's stipulation that God intends it for married couples), meaning Pan was a good frame work for the devil and all that has really changed since then was turning him red and giving him a trident.
Tactically the Beastmen also fit the Barbarian origin: light many troops that rely on ambush and surprise (more then one roman legion was lost by this kind of ambush), chariots which the Britons used against the romans (not effectively but this is a game not reality) and lastly they are like the Barbarians in that they are focused on skirmishing and raiding. Once upon a time all beastmen were skirmishers, which while effective against isolated villages is less effective against armies, which is why it was changed.
So the Beastmen have some pretty interesting roots once you 'pop the hood' on their design.
Occupy Drakwald
The thing that pisses the Beastmen off is that something like 1% of life in Middenheim controls 99% of the land! There are so many freaky beasts living in the chaos woods, combined with big Empire pushing around the people of the woods and ruining the environment for their own economic interests. And so the Beastmen have taken to their eternal campout against the Empire and it's regional castellan pretty boy, elector count Boris Todbringer.
Another thing that really pisses them off is that it's stated in the Orcs and Goblins codex that Forest Goblins on their spiders tend to murder herds wandering in the woods.
And that's not where the similarities end. The Beastmen are a bunch of lazy, shiftless, filthy degenerates that eat babies - no literally! That wasn't an anti-progressive political jab at all, it's the plain truth. The beastmen want nothing better than to just drink looted booze, eat/fuck other races and tear down everything that everyone has ever built - ever!
Origins
The Beastmen's origins seem to be something of a composite piece (and changes from edition to edition). On one account, they are descended from the myriad creatures that inhabited the Northern Wastes and migrated downward, accepting more stable forms from their reduced exposure from the polar fluxes of chaos and interbreeding with more magic resistant creatures. Another myth pins the Beastmen's origins as the mutated descendants of humans cast into the wild for being born a hideous half-man, half-beast creature (Now why the humans decide to throw all their mutant babies into the surrounding forest known to be populated with sadistic and vengeful goatmen born as mutants to humans and cast-off themselves is a bit of a mystery). The 6th ed Beasts of Chaos book says that when the polar gates collapsed, the Beastmen were made from animals mutating into men and men mutating into beasts while the 7th ed Beastmen book says that when Chaos was first released to the world the "primitives" at the time went mad, fucked some animals, generations later their descendants are the Beastmen. Wood Elves seem to have less of a problem with mutants, either because they resist chaos more/better or they kill such offspring immediately and never talk about it again, but that's just like, you know, a cultural difference.
Regardless, today's Beastman is more likely either the product of gangrape, spawned by a brief and unholy union from victorious Beastman raiders that managed to bring home some captive females from other races, usually humans, and it never ends well for the woman (However there was a chaos-tainted race that "reproduced" that way in the early days of WFB called the Fimir. But Games Workshop deemed it too Grimdark, even for them, and retconned it out of existence. So if that was too much for GW, I don't think they'd make it canon for Beastmen to reproduce that way), or they were spawned when a Beastman really loves a Beastwoman. We're not too sure how Beastmen "love" one another, but the fluff seems to imply that the Beastmen have to get really fucking hammered before hand with giant orgiastic feasts at their encampments around Beastmen Herdstones.
Herd Society
Beastmen society is organized around herds and ruled by a system of might makes right. In other words, what the biggest, strongest Beastman (or Beastwoman) says, goes. One would be forgiven in thinking that this automatically means that minotaurs would end up running the show since they are by far the biggest and strongest, but they're not the brightest thing on two hooves. Minotaurs specialize in wholesale slaughter, but aren't too keen on things like where to find food, who should keep watch or how to fix their shitty chariots. Lo, the Beastlord has his task cut out for him.
- Beastlords: the Beastmen in charge, the Alpha Male, they run the show for the other Beastmen with a combination of dastardly cunning and brute strength. They often delegate more benign tasks to their immediate inferiors, the Wargors.
- Wargors: the "trusted" (as far as Beastman loyalty goes) lieutenants of Beastlord, Wargors are pretty kickass leaders and fighters themselves. Oft seen carrying battle standards or leading Bestigor herds, or both.
- Bestigors: quite literally the best Gors, a ha ha </sarcastic laugh>. Strong, tough, heavily armed and armoured, the Wargors and Beastlords often arise from their ranks.
- Bray and Great Bray Shaman: tribal elders and spiritual leaders of the Beastmen, they interpret the will of Chaos and determine the best course of action for the heard. They are also the herd's wizards.
- Gors: the rank and file of the beast herd. Your average Gor is bigger, tougher and far nastier than your average human. He's also an unguloid with furry legs and a face that's a blend of bestial and human features. ALL Gors also feature prominent horns and/or antlers on their heads.
- Ungors: the untouchables even in beast herds. They are pretty close in size to humans, yet still feature particularly bestial features such as furry unguloid legs with hooves, a semi-bestial face and two small horn buds. Sometimes band together in scouting parties of Ungor Raiders when not used as slave labour to fix all the shitty Beastmen gear.
- Bray: Beastmen with no horns, the lowest of the low in Beastman society. In a society where life is short, brutish and nasty, their lives are by far the nastiest, most brutal and most especially shortest.
The Bulls
Nobody really knows why, but the Beastmen seem to be accompanied by a race of ferocious minotaurs, not that they're complaining. When the minotaurs aren't rampaging through the hardest parts of an enemy army, eating knights, drinking blood and shitting victory, they're often seen guarding caches of magic treasures deep in the Drakwald. They aren't a very bright group but their uncanny resilience, rape-tastic strength and general piss-your-pants scariness gets shit done for the Beastmen. There are also mutant varieties of the bulls that have long ago traded their sanity for fuck-off hugeness and other random shit.
- Doombulls and Gorebulls: The closest thing the minotaurs have to leaders, with the Doombulls being the larger, stronger and generally more daunting of the two.
- Minotaurs: Giant, bull-headed monsters that fuck near can't be stopped once they get to smashing shit.
- Cygors: 50 ft. tall, one-eyed minotaur mutant that can only see magic things. Likes to collect gigantic pieces of magic rock (more commonly known as temple columns) and eating the souls of mages... unless those tricksy wee things are causing him trouble, whereupon he'll just throw one of his gigantic rocks at it!
- Ghorgon: minotaurs that get a flair for cannibalism turn into giant-sized, four-armed killing machines with two of their four arms ending in scythe hands. They also have a penchant swallowing things whole and magically reknitting any wounds they may have had.
Other Critters
Being that the Beastmen are all a bunch of horrible monsters, they have a pretty high tolerance for other horrible monsters. Along with the minotaurs, the Beastmen's ranks are supplemented by other creatures used for various tasks from beasts of burden to cavalry to shock troops to cannon fodder.
- Warhounds: just like the ones starved and taunted by the warriors of chaos, but instead starved and taunted by Beastmen. Used for a fast and cheap screen
- Tuskgors: what essentially look like warthogs, they're most often used to pull the herd's shitty chariots.
- Razorgors: bigger, nastier, mutant tuskgors. They are either loosed in packs or used to pull chariots. Why the Beastmen use pigs as pack animals and eat horses instead of the other way around is a bit bizarre, but might have to do with how flighty horses can get around large, carnivorous animals.
- Centigors: The torso of a Gor fused onto the body of a horse with three hooves per foot, by the looks of it. Totally ungainly and butt-hurt over it, they take to stealing beer, wine and spirits brewed and distilled by other races and getting shit-faced daily to forget that fact. They act as cavalry to the Beastmen.
- Harpies: identical to Dark Elf harpies, may or may not be the Beastwomen with which the Beastmen procreate. Used primarily as flying shock troops.
- Chaos Spawn: not sure if either heavily mutated Beastmen or just normal spawn, that which must not be named are goaded into battle... somehow.
- Jabberslythe: arguably the ugliest thing in all of WHFB. Said that not even the clearest pools will reflect its image, or maybe they just don't stay clear for very long. Either way, this is yet another giant powerhouse of a monster using its ugliness as a shock weapon to get the Beastmen's enemies to kill themselves.
- Giant: the warhammer giant is at the beast's disposal to jump up and down, yell at people and stuff them into its pants.
Notable Beastmen
- Khazrak The One-Eye
- Taurox the Brass Bull - Violent bull-freak made of Brass after eating one of Khorne's daemons.
Morghur the Master of Skulls-The closest thing to a central leader the Beastmen have. This guy not only corrupts and mutates anything in his path, every time he's killed, he simply resurrects and starts all over again. He's considered the greatest enemy of the Wood Elves and the chosen prophet and champion of the Chaos Gods to his people.
Malagor the Dark Omen- The Bray Shaman of all Bray Shaman, this Beastmen is not only a powerful sorcerer and a cunning manipulator he also has a pair of black raven wings that enable him to fly. He greatly resembles an old representation of old Nick called Baphomet.
Gorthor the Beastlord- The greatest Beastlord to ever live, he united all the Beastmen or the Middle Mountains, pioneered the use of chariots, brought down two provinces of the Empire and in addition to his fighting skills was a tactical and strategic thinker.
In 40k
Yes, once upon a time, Beastmen were playable in Warhammer 40,000. And then they disappeared. But now they have reappeared, with a mention in the core rulebook and a presence in the Heretics & Renegades army list printed by Forge World! Back in 3rd edition, Beastmen and other mutants were the byproduct of Genestealer Cults, which were a specific type of Genestealer infiltration, formerly called a Genestealer Clan, that started worshipping Chaos and the Ruinous Powers, thus becoming a Genestealer CULT. The army allowed for use of Genestealers, Beastmen, mutants and Demons. Later, the term Genestealer Cult was used for a general Genestealer infection, and the beastmen were shuffled off to the side in favour of a Genestealer Cult list having nothing to do with them, but that's fine as they then turned up in a playable mini-army in the Witch Hunters rulebook as an example of what the Witch Hunters fight against (called mutants in this case), and they also showed up again in the Eye of Terror codex, in the Witch Hunters case it's because mutations like that happen naturally in 40K, they're just usually killed when they're born and the army in question didn't follow the Imperium's teachings, and in the second case it was directly due to Chaos making a lot of mutants.
Now, they exist mainly in the fluff as a barely-tolerated strain of abhuman whose main use in the Imperial Guard is to act as meatshields so they can atone for being mutants. Some things never change.