Eight Celebs Go Undercover

Eight Celebs Go UndercoverSteven Gordon Fessey

When you're a celebrity, staying incognito is key. Best way to achieve said results? Disguises. Just ask Joaquin Phoenix.

Daniel Radcliffe and Rupert Grint attended the Reading Festival in the U.K. and took a tip from his playbook by showing up in some oh-so-inconspicuous matching helmets and goggles. Of course, no one noticed them at all as they rocked out to the punk band Gallows. Below, check out some other great celebrity disguises guaranteed to promote attention ... and sometimes anonymity.

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Drew Barrymore I almost didn't recognize Drew Barrymore with her shark cap and silver face-paint, when she and BF Justin Long snuck away to a Miami Marlins game.

Keira Knightley What's the best way to avoid drunken paparazzi pics after your 21st bday? Wear a pig mask on your way out like Keira Knightley.

Paris Hilton Psst, Paris. I know it's you. Despite the wig and hat.

Either Prince Harry is really feeling the '70s, or this is a bad disguise. [Click HERE to see the photo.]

Mary-Kate and Ashley Olsen Look it's two twin rabbits! Oh never mind ... it's just Mary-Kate and Ashley Olsen. They almost had me there.

Is that Lily Tomlin? No silly, it's Heather Mills. More importantly, is she starting a "disguise line" along with her eco-friendly line? [Click HERE to see the photo.]