4. Diane - Love Potion #9
I don't know how she's managed it, but somehow Sandra Bullock has made a career out of making people forget how attractive she is. Seriously, how many ugly duckling films has she made over the past 20 years or so? A lot. But the most charming has to be Love Potion #9, where she and Tate Donovan furiously compete to be the most adorable person ever. Two scientists (read: hopeless nerds) get their hands on a potion that makes them irresistible to the opposite sex. And so the hijinks begin. Bullock throws unparalleled charisma into the character of Diane, and her gleefulness at finally being noticed by men is a lot of fun to watch. As she slowly comes out of her shell and becomes more confident in herself, both Donovan and the audience are struck with the realization that she's pretty much the perfect woman. She's brilliant, of course -- her various diplomas are proof of that. But she also has this fantastic personality, the shy girl that people are finally starting to pay attention to. When the prince of England falls in love with her, it would be really easy for Diane to get a big head about herself. People change, and nothing changes them more than money and fame. But she remains the same sweet, earnest girl that she always was, even when she's got the future King of England on her arm.