I remember when my brother and I were reading the Harry Potter series, we both loved the adorably odd Luna Lovegood, so I was delighted to find her well cast and a fun focal point of the recent Potter movies.
The thing I love about her in the films is that despite being a little bizarre, she often strikes at the heart of the truth in the dire world of magic, giving Harry the advice he needs when he needs it. She is also wonderfully oblivious to other people's opinions, even the Ministry of Magic's. She marches contentedly to the beat of her own drum, while wearing some crazy "Fashion Don'ts"...which of course makes me like her all the more. :)