POPSUGAR Celebrity Halloween Mary-Kate Olsen and Ashley Olsen Halloween Pictures by Lindsay Miller 10/05/11 18 Shares Like us on Facebook Sign up for our daily newsletter > Previous Photo 1 of 11 View on One Page ADVERTISEMENT ( more slides) Next Share This Link Copy 1 Mary-Kate Olsen and Ashley Olsen Halloween Pictures Previous Photo 1 of 11 View on One Page ADVERTISEMENT ( more slides) Next Read More StyleMintHalloweenAshley OlsenMary-Kate Olsen Ashley Olsen Mary-Kate and Ashley's 75-Year-Old Muse Is About to Become Your New Style Icon 90 Reasons to Celebrate Mary-Kate and Ashley's Style 13 Moments That Made Us Wish We Had a Stylish Sister by Our Side Hold Up — the Olsen Twins Still Might Be on Fuller House After All Mary-Kate Olsen Mary-Kate Olsen's Bold Shoe Choice Is Not What We Expected Mary-Kate and Ashley's 75-Year-Old Muse Is About to Become Your New Style Icon 13 Moments That Made Us Wish We Had a Stylish Sister by Our Side She Wore THAT? 25 Then-and-Now Style Pics From Your Favorite It Girls Halloween Sofia Vergara's Modern Family Halloween Costume Is the Best Throwback Ever 13 Nights of Halloween: Here's the Full Lineup For ABC Family's Annual Marathon! This Year's Pumpkin Spice Offerings, Ranked From Worst to Best 10 DIY Costume Tips From Etsy's Handmade Pros POPSUGAR, the #1 independent media and technology company for women. Where more than 75 million women go for original, inspirational content that feeds their passions and interests. Be in the Know With OurCelebrity and Entertainment Newsletter Personalize Young Hollywood TV A-Listers Movies Sign up with facebook or By signing up, I agree to the Terms and to receive emails from POPSUGAR.