5. Renee Zellweger - Bridget Jones (Bridget Jones' Diary)
Whoever decided to cast an American actor as a character whose defining trait lies in her unbelievable Britishness had some serious balls, you'd have to admit. Whereas Kate Winslet or Toni Collette might have been far easier and better accepted choices at the time, it was Renee Zellweger, an actress we'd all just seen in
Jerry Maguire, who would ultimately sign on to star in Helen Fielding's modern reworking of
Pride & Prejudice. On a surface level, at least, this looked like the ultimate miscasting: an attractive, slight American woman. Huh? It was only when Zellweger proved her dedication to the role (she put on weight and made herself look less like a Hollywood star and more like somebody you'd see wandering around Camden market) that the world came to accept that this was bizarre casting they could come to terms with. Although a British actress might well have embodied Bridget's natural mannerisms with far better ease than Zellweger, she pulls it off with charm and gusto. The character is slightly different from the original novel as a result, but no matter: you did good, Renee.