Belgos (male drow vampire)
Where is he found? Vault of the Drow
Who does he serve? His mistress the succubus Silussa.
What's his job? Master of bats and rats. Bodyguard?
Tloques-popolocas (male human vampire)
Where is he found? Hidden Shrine of Tamoachan
Who does he serve? The vampire-god Zotzilaha.
What's his job? Master of Outsiders and sleeping.
Maskaleyne (male human vampire)
Where is he found? Iuz the Evil
Who does he serve? The demigod Iuz.
What's his job? Boneheart member and governor of Grabford.
Prince Ferrenan (male human vampire)
Where is he found? Ivid the Undying
Who does he serve? No one, House Cranden, or at one time, animus Overking Ivid
What's his job? House Cranden ruler of Blacksplinter.
Vlad Tolenkov (male human vampire)
Where is he found? Queen of the Demonweb Pits
Who does he serve? The demon-queen Lolth
What's his job? Aspiring warlord, ruler of Nightworld.
Ctenmiir (male human vampire)
Where is he? White Plume Mountain
Who does he serve? The wizard Keraptis.
What's his job? Cursed to guard treasure.
Nanna, Dannen and Willow (human vampires, two female, one male)
Where are they found? The Doomgrinder
Who do they serve? Two of these former druids serve the third druid. No spoilers.
What's their job? Wandering and druid stuff.
Okay, that last trio is rather different than the standard Dracula trope vampires before them, but being druids they are likely going to remain neutral hermits anyhow. That's all for now. To sum up, yes there are many vampires in Greyhawk, and in positions of great power; just not any kind of organized vampire families or bloodlines of note. Maybe that's a good thing.