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Isaac Brekken/Getty Images for Clear Channel
Of course, we had to include the Queen of Pop in our gallery since she's been inspiring some of the best Halloween costumes for years in the biz (red leather suit, anyone?). But this year, Brit-Brit's been rocking a toned-down style (no snakes in sight), so it's even easier to dress like the fierce femme. Just rainbow dye you're hair, put on a sexy short dress and be sure to master those awkward loveable X Factor faces. Come on, you know the look we're talking about.