I word that was given true meaning by JK Rowling in the legendary book Harry Potter and the Deathly Hallows.

People who don't know anything about the process of a book to film adaptation. Clueless and idiotic "fans" who slate the Harry Potter films because they are "not like the books." These people fail to recognise that books and films are entirely separate mediums and entities.

They often resort to hating the director, not taking into account that there are other people involved in the filmmaking process, including the writers and WB Studios who place pressure on the team to adapt source material from a 700 page novel into a 2.5 hour film with budget constraints.

Potter purists lack any knowledge and common sense; they moan and whine about the slightest change, cut and/or addition in the films and are ignorant to the fact that such changes are necessary for the benefit of cinematic style and substance.

They also do not rate a film on its cinematic structure (EG editing, cinematography, pacing, score etc...) but on how much it was like the book.

Basically, they are generally a group of ungrateful haters, which Jo Rowling would be extremely ashamed to call "fans".

Joanne Katherine Rowling. Writer of many short stories and the famous Harry Potter series. She has written the following published books:
Harry Potter and the Philosopher's Stone/Harry Potter and the Sorcerer's Stone
Harry Potter and the Chamber of Secrets
Harry Potter and the Prisoner of Azkaban
Harry Potter and the Goblet of Fire
Harry Potter and the Order of the Phoenix
Harry Potter and the Half-Blood Prince

these are all great books, as many have said. They are not meant to convert people to 'devil worshipping' or anything else that the Pope and/or other people have acclaimed to. It is merely for entertainment purposes and a job for a well-deserving mother.