Like its offshoot Warhammer 40000, Warhammer Fantasy Battles contains many playable factions and a large number of named characters.
For the tropes that apply to these characters during the end times, see here. For tropes that apply to them as seen in Total War: Warhammer and associated titles see here.
The playable factions are:
The Human Nations
Humans are a relatively young race in the Warhammer
world. They do not remember the departure of the Old Ones or the first coming of Chaos, nor do they have the depth of knowledge and wisdom of the Elder Races. However, they have grown to be a dominant species in the world, dwarfing the Elder Races by their numbers if not their sophistication. Unlike other races, Humans are a diverse species, having as many corrupted and cowardly individuals as they have brave and wise heroes. For better or worse, they have taken a central role in balancing the fate of the world.
There are dozens of human nations, but only the Empire and Bretonnia are playable. Humans do tend to dominate the Dogs of War list, however.
The Elder Races
Old, declining, yet proud beyond measure, the Elder Races were present in the Dawn Times, when the first of their kind were sculpted by the hand of the Old Ones themselves. Thus, they tend to be far more resistant to Chaos than humans. In times past all of them built magnificent civilizations, grander than anything Man has achieved so far. However, millenia of strife and tragedy have inevitably led to their decline, and they are now a shadow of their former selves. Despite all this, they still represent some of the most formidable forces of the world.
The Wind of Death blows strong in the Warhammer
world, and the dead have long and bitter memories. The Undead are the logical result of the short-lived humans' efforts to achieve immortality, no matter the cost. Nagash, first of the Necromancers, was responsible for developing the malign art of raising the dead to serve a master, which indirectly contributed to the rise of the Vampires and their diverse bloodlines, who control armies of cadavers of all sorts and are megalomaniacal in their pursuit of eternal un-life.
The Forces of Chaos
Beyond the veil of reality lies the Realm of Chaos, home to four gods so powerful one of them alone could snuff out the world and its gods along with it, and would do so gladly. Having first invaded the world millenia ago only to be barely repelled by the combined might of the Elder Races, the Chaos Gods and their Daemon armies cannot easily walk through the world and are barely contained to the poles. Now the Forces of Chaos, mortal minions of the four gods corrupted by their influence or lured to their side by promises of power, lie in wait for the right time to destroy the world and watch it burn. And that time is approaching...
A malevolent and diabolical race of ratmen whose warrens span a global inter-continental underground empire known in their tongue as the Under-Empire. The Skaven are a cruel and vicious species whose military power and incomprehensible numbers have the potential to smother all the kingdoms of the Old World, a destiny the ratmen believe is inevitable. Scheming and treacherous, the Skaven consider themselves the supreme master race, undeniably superior to all other civilizations in the Warhammer
world. They are constant enemies of the Dwarfs, the Night Goblins, and all non-Skaven races. And of each other, if we're honest.
The Greenskins are considered by many to be the scourge of all civilization. Big and mean or small and mean, these green-skinned monstrosities can be broadly categorized into two species: The large and brutish Orcs and the small and cunning Goblins. Supremely violent, they exist in a permanent state of war against anything and anyone they can see. Time and again, Greenskin hordes arise without warning and lay a great swath of destruction that has no direction or purpose other than simple violence, an ever-increasing mass of warfare that has the potential to dominate and cover the entire world in a seething green tide.
Hulking, brutal humanoids who began as members of the Dogs of War but were expanded into a full-fledged army in their own right in late 6th edition.
Comparatively minor elements of the Warhammer setting, these factions may have had army books/codexes of their own in past editions, but currently do not have that kind of support and survive mostly through the support of older fans and knowledge.