Katy Perry: Style Evolution (PHOTOS)

10/24/2011 07:26 pm ET | Updated Oct 11, 2012

"One of the Boys" was the breakout album that thrust Katy Perry into the spotlight. But the songstress's ultra-girly, retro-glam style makes her anything but.

Whether Perry is rocking a playful romper, pinup-worthy frock or sophisticated, floor-sweeping pastel gown, she's always favored pieces that are flirty, fun and feminine.

To celebrate Katy's 27th birthday today, we're taking a look back at some of her best ensembles.

In related news, see why Perry made the list for 2011's most shocking bikini moments.

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