Let us go out this evening for pleasure... The night is still young!
Oh, fuck the hell yes.
One of the only incarnations of Vampires that doesn't suck so badly that other Vampires are sucked into it, the Vampire Counts are Warhammer Fantasy Battle's version of the classic Vampire - and in a bit of irony that catches most off-guard, are total fucking badasses who almost took over the entire fucking world before the armies of man got their shit together. Powerful as all fuck and just as evil, the Vampire Counts in the Warhammer universe long to plunge the entire world into a holocaust of darkness and despair, ensuring that the entire land is wholly under their thumb and those mummy sons of bitches and filthy mortals know their place as slaves and food.
Basically it's an entire army of Gothic Horror vampire lords, seeking to conquer the lands not just to appease their own massive egos and pride, but to ensure their all-encompassing need to feed. The classic intelligent monsters and consummate overlords of evil, WHFB's Vampire Counts are pretty much the best of what Vampires can be, and sure as fuck a welcome departure from this shit.
A long-as-hell time ago, even by Warhammer Fantasy standards, there was a powerful Priest of Khemri named Nagash, who was such a thorough badass that he became not only the first Necromancer in Warhammer Fantasy's universe: He literally created the first undead. His dark arts he learned from a trio of Dark Elven Sorceress , who taught him how to manipulate the energies of Chaos using dark rituals involving heresy and human sacrifice. He killed them in a magical duel, poisoning one, ripping another to shreds and crushing the third before counsuming their souls; many on /tg/ would say this is the way to deal with an Elf.
Three thousand years later, still a pain in the ass.
After this, there was no stopping the guy - he communed with Daemons and the spirits of the dead, seized the kingdom for himself from his brother, and used his Necromantic magic to greatly expand his own lifespan. Suffice to say, this scared the shit out of the other kingdoms around Khemri, and they attempted to kill him. Despite having an endless army of the dead and loyal followers, Nagash was finally cast down, though he fled and would eventually emerge once more as a liche, continuing to, as many threats in the Warhammer universe have, be a constant thorn in the side of the armies of man to this very day.
During his tenure as King of Khemri, Nagash decided it would be an awesome idea to run a real-life version of Dwarf Fortress during the creation of a massive necropolis that came to be known as the Black Pyramid, so named for the black stone that made it up. This is arguably the coolest-named monolith in history, second only to the fabled Prismatic Pyramid or Pyramid of Fire-Sharks.
After the fall of Nagash, it went undisturbed for years, since nobody wanted anything to do with a giant monolith that was related to a man who pretty much came within striking distance of ruling the desert kingdoms. At some point, a woman named Neferata - the cousin of the queen of Lybalas - broke in and made off with some of Nagash's magic books, which were later called the Nine Books of Nagash.
Using the corrupt lore she found there, Neferata discovered a recipe for the Elixir of Life, a blood-draught that would extend one's lifespan. Doing her own research on it and "refining" it, she eventually created a new version of the Elixir - called the Elixir of Damnation - she then downed it, and, ultimately, shared it with her most powerful followers, before they slowly converted the entire court.
Naturally, this led to problems. The rampant feedings of Neferata's followers quickly became too much to ignore, and Neferata herself tried to convert her cousin - and failed. Suffice to say, the other armies of the desert kingdoms fell upon them like sacks of thunder, and they wound up scattering, regrouping only when they met up with the now-undead Nagash. The Vampires quickly became generals of Nagash's armies, and, with the overpowering forces they added to Nagash's cause, turned on the armies of men chasing them, and began to systematically usher in what would have led to a zombie apocalypse.
Their advance was short-lived - Sigmar showed up, and, when Nagash called for aid, the Vampires were too arrogant to actually help out, and Sigmar cut him down in short order. In retaliation for this, Nagash laid out a curse on the Vampires for this offense: for their refusal to come to his aid, they would forever be weak against the power of Sigmar. Since that time, they've been vulnerable to both sunlight and the power of faith. The Vampire advance fell apart quicker than Boatmurdered, and the bulk of the Vampires retreated to the lands of Sylvania, where the various Vampires would scatter to follow their own agenda, not unlike several other groups in the Warhammer 40,000 universe.
There they continue to menace the armies of man with periodic invasions of undead, death, and horror.
They're fucking pre-suckass Vampires. What the fuck do you want?
 Vampire Bloodlines
The Von Carsteins are your old-school Vampires of the Dracula-inspired variety. Vlad Von Carstein, the lead of the family, was the one who first tainted the human aristocracy of Sylvania with undeath, leading them to become the badass European Vampires they'd eventually become. The Von Carsteins were kind of unusual in that they realized that keeping the living populace safe meant easier meals. This didn't mean he eased up on being badass, however - instead, Vlad violently brought a lot of the rebellious nobles in line and actually managed to unify much of Sylvania's vampire nobility for a while, which led to a second Vampire invasion of Imperial lands, this one far more effective than the first. When Vlad himself was killed by Wilhelm the Third, his wife Isabella could only keep things together for so long before Konrad, his psychopathic immortal son who is in many respects analogous to a WHFB version of Kharn quickly caused the advance to grind to a screeching halt. Konrad eventually got killed, and their second son, Mannfred, arose, though now he is believed to have been killed as well.
The Lahmians, named for the monster that drinks the blood of Children, are an almost-entirely-female vampire clan, who descended from Neferata, the woman who started the Vampires off in the first place. Having pissed of just about every other Vampire clan due to their involvement with this nonsense, her followers currently occupy the once-dwarven lands of the World's End Mountains. Not a whole lot is devoted to them in more modern times, indicating that they are arguably one of the less-popular factions, Lesbian connotations aside.
Formed by Abhorash, the fuckingest of Vampire Warriors, the Blood Dragons are the martial vampires, and fucking awesome. Honorable to a fault, though evil-as-hell, They will never refuse a challenge and excel at absolutely curb-stomping anything put against them in combat. Consummate warriors, they live to fight, and they believe that only cowards feed upon the weak - the only ones that Blood Dragons will willingly feed on are powerful warriors and monsters. As such, they are capable of resisting the thirst better than the other clans, and, due to their badassery, are arguably one of the two favorite factions of Vampires for /tg/ in the setting.
Following distantly in the footsteps of Nagash, the Necrarchs are Necromancer vampires and loremasters. Whereas other Vampires focus on sorcery, martial pride, or a mix of the two, the Necrarchs focus entirely on Necromancy and thus have vast armies of the undead at their disposal. A common joke is that they'd be studious gits and/or faggots.... If they didn't GET SHIT DONE.
The Strigoi are horrid-looking mutant Vampires, closer to Ghouls than traditional Vampire-kind. They not only drink their prey's blood - they go all the fuck out and devour their prey's flesh as well. Hated and feared even by their own kind, they are easily the kings of ripping and Tearing and have more Ghouls at their disposal than any other bloodline. Do not let the fact that they are freakish abominations convince you that they are not FUCKING BADASS.
 See Also
 External Links
Carpe Noctem, the main Vampire Counts army forum