An individual who is extremely infatuated with the Harry Potter series. Fans of the movies alone don't count. The difference between a mere fan and a Potthead is the difference between having read all of the books and having worn round glasses and a fake scar to not only the premiere of the movies, but the release date of the books.
A: Ohmygodohmygodohmygod I can't wait for the seventh book! I've already read Half-Blood Prince twelve times and -- *gasp* Do you think Jo's going to kill Harry just to be spiteful?? *cries*.
B: Jesus Christ, you're such a Potthead.