Human servants of vampires

30 Days of Night is on, and it got me thinking about the Ben Foster character. A lot of vampire movies have a human or two who serve as some kind of accomplice or servant to a vampire master. They are almost like a witch's "familiar," in some ways... almost a pet.

Dracula had Renfield. In Salem's Lot, Barlow had Straker. In Fright Night, Jerry had Billy Cole. In The Forsaken (2001) (forgive me for even knowing what The Forsaken is, but I happened to watch it fairly recently, God help me) the Johnathan Schaech character had Pen, the Simon Rex character. In 30 Days of Night, the vamps had the Ben Foster character.

Googling around, I see people seem to use different terms to describe these human servants. They get called drudges, thralls... I thought I was being original in associating them with witch familiars, but Maybe I read that somewhere before, because I see other people saying the same thing online...

Anyone have anything to say about this type of thing?? Any movies I am forgetting, with a character like Renfield, Straker, Billy Cole, etc? Or, any names for them that I haven't come across?