Being in Harry Potter is like being in the Mafia. Once you are in, you are never really out.

I think that the process of making a film is an underrated factor in how that film turns out.

I think I'm always very naïve. With 'Kill Your Darlings' and 'Horns', I'm like, "Why wouldn't everybody love this?" But I guess it's going to divide people in some ways. But if you're willing to go with it and suspend your disbelief, you're going to get something amazing and something unlike anything else.

I think it's useful, as a famous person, to have as little separation between the perception of you and how you really are - because otherwise I'd be sitting here thinking I'm keeping secrets, and wondering when you're going to find out.

I'm sure when I have a nostalgic, teary moment in 10 years time, I'll try to put the glasses when I was 10 on and cry to myself in front of the mirror

I'm an atheist, but I'm very relaxed about it. I don't preach my atheism, but I have a huge amount of respect for people like Richard Dawkins who do.

If you like the book, you'll hate the movie.