Buffy Slays!

We can't talk about vampires and not talk about Buffy the Vampire Slayer, the cult TV show by Joss Whedon which ran for seven seasons.
Based on the 1992 movie of the same name, Buffy Summers is a teenage girl attending a new school in Sunnydale, California. She is also the Chosen One, granted supernatural strength and speed so she can take down vampires, demons and the forces of darkness. 
Over seven seasons, Buffy grew from a 16 year old girl, into a strong young woman, who faced many horrors and saved the world once or twice. While vampires were one of the main foes on the show, it also introduced Angel, a vampire with a soul who fought on the side of good. He even got his own spin off show. 
A lot of the monsters of the week were metaphors for the horrors we face in real life as we grow up. The kid who feels invisible, actually turns invisible and it is a bad idea to be a teacher's pet!
Who was your favorite vampire on the show?