The Masquerade - These individuals once were humans. Until they were changed into vampires. The term they use is the Embrace. Once changed, they cannot endure the light of the sun, although most of the other common myths about the undead do not necessarily apply. Many of them, but not all, live under an elaborate Masquerade, pretending to still be human, and that there is no such thing as vampires.
Humans are happy to accomodate.
Their lives are usually full of intrigue and politics. Their adversaries include werewolves, who think they are an affront to Gaia because they are unnatural, or human hunters who know the truth about them. And unlike the werewolves in the movies are not forced to turn into uncontrollable monsters by the rising of the full moon. They were given the mission by Gaia, goddess of the earth, to protect her world from destruction via pollution, carelessness, etc. And her chosen warriors were given the form in which they could walk among man or revel in the kingdom of nature.