Rihanna rocks the mohawk! Katherine Heigl goes brunette! Michelle Obama chops her 'do (or so we thought)! They may not be our nation's most pressing news stories, but these celebrity hair transformations certainly had our heads turning in the beauty-sphere. Craving a hair makeover but afraid to pull the trigger? Follow these style tips and tricks to make sure your next hair transition goes smoothly.

Rihanna's no stranger to a daring new 'do, but even her biggest fans were shocked to see her go from sexy pixie cut to this gravity-defying mohawk. If anyone can pull off this space age-punk hairstyle, it's her. If you're daring enough to try a similar 'do, style it with an extreme-hold product like Sebastian Professional Mousse Forte, $17.50.

The "Grey's Anatomy" star had heads turning at "The Ugly Truth" premiere when she revealed a chic, auburn updo, a drastic change from her signature blonde glam curls. If you're considering darkening your tresses, do damage control by using a shine-enhancing and repairing mask like Kerastase Chroma Reflect Masque, $56.00, weekly.

It's official: Our nation is obsessed with the First Lady's beauty and style, so of course her recent "cut" had people talking. After this photo was taken, her hairstylist revealed he didn't actually cut her shoulder-grazing bob. He simply tucked and pinned the hair back to create the illusion of a tightly cropped bob. Check out this easy how-to to create a similar faux-bob to Obama's.

Our favorite film sweetheart recently ditched her auburn "modern flapper" style for tousled, sun-kissed tresses. Is your formerly cute bob starting to bore you? We have the perfect sexy, beachy style how-to for you.