"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.