What makes a celebrity into a fashion icon? While impeccable taste certainly helps, consistently donning a garment or accessory that soon becomes a signature is the real key.

Here, some of the most iconic women in history and their hallmark statement piece -- from Michelle Obama's vibrant cardigans and Gwen Stefani's blazing red lips to Nicole Richie's hippie head wraps and Jackie O's oversize shades.

What's your signature style piece?