Vampires -- best supplement?

[Teflon Billy]

Fang and Fury is great, as it GURPS Blood Types

 

[Warrior Poet]

Blood Types is one on the all time great monster supplements for any RPG.

GURPS has come to occupy an interesting situation in game products, whereby the core rules set is average (I have no problem with it, but I know many don't like it), but the supplements are some of the finest available (in terms of content, if not necessarily production) and are useful for practically every other game system out there (conversions have to happen for different systems, obviously). GUPRS supplements are, for the most part, awesome.

That being said, I'd also add GURPS Horror to the list. It's not solely on vampires, but it can add a lot to any vampire game, plus it's got loads of good stuff for all kinds of other games, and it's got a good sense of humor written right into it. A+ product (the art's a little lacking, except the cover, which is a Michael Whalen painting).

Warrior Poet