Every year, PEOPLE magazine puts together a list of the 100 folks on the planet it deems the most talented, inspiring, and, yes, gorgeous. The 2009 World's Most Beautiful People issue hits newsstands May 1, and features today's most striking stars. (Get a sneak peek on People.com.) But what about the classic beauties of decades past? LIFE asked Liz Sporkin, editor of the PEOPLE special issue, to name the 20 classic female entertainers who fit the bill. First up: Grace Kelly, the stunning Oscar-winning actress who became a real-life princess in 1956 and has defined Hollywood elegance for decades.