Denim has undergone a major evolution since Marilyn Monroe added sex appeal to true blue jeans. Jane Birkin slipped her gamine stems into frayed flares in the '70s. Nothing came between Brooke Shield and her Calvins in the '80s. Cindy Crawford was an all-American bombshell in straights in the '90s. The Olsens introduced us to the skinny jean in the '00s and now it seems that everyone's favorite silhouette is a frayed-hem flare. Take a look at our favorite celebrity moments throughout history.