7. Reese Witherspoon
Anybody that has seen Walk the Line will find it beyond baffling that Reese Witherspoon continues to allow herself to be cast in trash like This Means War, Four Christmases, Water for Elephants and so on. Back then, nobody thought Reese Witherspoon was going to make a good June Carter Cash - this was the actress who was the lead in Legally Blonde. She had shown some promise in Alexander Payne's Election and Cruel Intentions, but it seemed inevitable she would become the next big rom-com star, earning the big money whilst performing lazily written scripts, and she confirmed as much with appearances in Legally Blonde, its sequel and Sweet Home Alabama. But then Walk the Line happened, and it was clear there was a star in her. Starring opposite the mercurial Joaquin Phoenix, she lit up the screen, and dazzled with fierce energy. She sang her own songs, and melts the screen with her brimming sexuality; in short, it's the performance of a lifetime. That performance pretty much came from nowhere, and it was always going to be nearly impossible for her to top - she won an Oscar after all - but it is so dismal, to see an actress go from such a wonderful performance back to silly rom-coms like This Means War.