Loads of top thinkers are going to a big conference over the weekend and will try to work out why the show is so popular.
They will also be looking at the spin-off show Angel as they try and find out what fascinates people so much about TV shows all about blood and magic.
The conference at the University of East Anglia in Norwich (UEA) is called Blood, Text and Fears, and will hear from experts on subjects like film, drama, education, law and religion.