Who's That Girl on Glamour's 'Hair Flip' Issue?

Who’s on the cover of Glamour’s February issue? You’ll have to wait until next month to find out. But depending on your celebrity hair knowledge, you may be able to guess the magazine’s cover girl from her picture on the back cover, which shows only the back of her head. (Here are a few hints: She’s famous for her long, brunette tresses, has a passion for nail art, sings and acts, and was married...