Tiffani-Amber Theissen — in 1989 and 2012
As perky Kelly Kapowski, Tiffani-Amber Theissen taught us everything we needed to know about how to be totally popular and awesome at everything — and we loved her for it. She went on to cause trouble on Beverly Hills: 90210 as conniving, bitchy Valerie Malone, and that made us love her even more. Over the years, the 38-year-old has jumped from sitcom to sitcom, but landed on the USA Network's police procedural dramedy White Collar with hottie Matt Bomer in 2009 and has been there ever since. These days, Tiffani-Amber looks better than ever, and it's clear our girl crush on her will never die!