Call it the Rihanna effect. For December, bubbly Kate Hudson tries living on the edge for Elle UK and sweet Natalie Portman mimics Cameron Diaz's fierce V cover right down to the suggestive open mouth. Then there's classy Nicole Kidman looking like—and talking about—sex in British GQ.

The most ironic part is that real-life edgy actress Kristen Stewart has transformed into a sensual, high-fashion glam goddess for Harper's Bazaar.

Or is it that ironic?

Nicole and Kate are currently promoting their upcoming burlesque musical, Nine, which explains this and this. Natalie wants to be taken seriously, so her girlie-girl image just doesn't cut it. And as much of a tomboy as Kristen tries to be in her own life, she's a soft beauty in Twilight, and New Moon is just around the corner. So let's skip Kate, Nicole and Natalie this time around and just enjoy the stunning editorial the normally grungy Kristen did with Robert Pattinson…

Romantic lover in Prada and Cesare Paciotti pumps.

Pure seduction in Versace.

High-fashion drama in Alexander McQueen.

To see other high-profile stars morphing on magazines, visit mystyle's Cover Girls: Is That Really You? gallery! 

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