Celebrity The Stars Go Trick-or-Treating By InStyle Editors InStyle Editors Facebook Instagram Twitter Our editors and writers comprise decades of expertise across the beauty, fashion, lifestyle and wellness spaces in print and digital. We prioritize journalistic integrity, factual accuracy, and also having fun with every story we share. InStyle's editorial guidelines Updated on November 2, 2009 @ 11:31AM Pin Share Tweet Email Trending Videos Photo: Nicepic/MeetTheFamous The Stars Go Trick-or-Treating 01 of 10 Ashley Greene and Kellan Lutz Denise Truscello/WireImage Eclipse stars Kellan Lutz and Ashley Greene celebrated fright night in Sin City, hosting the Yelloween party at Tao Las Vegas. "So excited to dress up for Halloween and my costume!" Greene Tweeted about her peacock costume the night before the bash-while Lutz went as Batman sidekick Robin. 02 of 10 Brad Pitt, Angelina Jolie, Zahara and Shiloh Ramey Photo Fright night was a family affair for the Jolie-Pitts, who hit the streets of L.A. for some trick-or-treating. While Brad dressed up as DJ Lance Rock from the hip kids show Yo Gabba Gabba, Zahara played Bat Girl, Shiloh kept her tomboy image intact as a fighter pilot and mom Angelina sported some bloody face paint. 03 of 10 Michelle Obama Jonathan Ernst /Landov/Reuters First lady Michelle Obama made the purr-fect catwoman when she paired kitten ears with a leopard-print sweater to hand out candy-the selection included dried fruit and M&M's according to HuffingtonPost.com-to local school children at the White House. President Obama exercised his right not to dress up, opting for a more casual ensemble of a sweater and dress pants. 04 of 10 Miley Cyrus Albert Michael/startraks She didn't get the night off, but Miley Cyrus gave peace a chance when she channeled Pocahontas to perform at a special Halloween concert at Freedom Hall in Louisville Kentucky. 05 of 10 Heidi Klum and Jessica Alba Alexandra Wyman/WireImage Though she gave birth to daughter Lou Sulola Samuel just a few short weeks ago, nothing could stop Heidi Klum-almost unrecognizable in her crow costume-from hosting her annual Halloween bash. The Project Runway host welcomed guests Paris Hilton, Jessica Lowndes and a Dora the Explorer costumed Jessica Alba to Hollywood's Voyeur Club for the fright night fete, presented by MSN and SKYY Vodka. 06 of 10 Nick Cannon and Mariah Carey Mike Coppola/Getty Known for their couples costumes-last year they attended a party as milk and cookies- Nick Cannon and Mariah Carey were in Halloween heaven when they attended a party at New York City's M2 Ultra Lounge. 07 of 10 Gwen Stefani INF Photo Dressed as a glamorous gunslinger, Gwen Stefani toted her tiny dinosaur, son Zuma-already enjoying one of his treats-to a Halloween party in Los Angeles. 08 of 10 Michelle Trachtenberg Dimitrios Kambouris/Getty Gossip Girl star Michelle Trachtenberg marked Halloween as Marie Antoinette at the 2033: Adult Playground bash, held at New York City hot spot 1Oak. 09 of 10 Blake Lively and Scott Sartiano Dimitrios Kambouris/Getty Also at 1Oak for the Svedka Vodka bash, sexy flight attendant Blake Lively posed with club owner Scott Sartiano before heading inside to join boyfriend Penn Badgley for the festivities. 10 of 10 Christina Aguilera Nicepic/MeetTheFamous Christina Aguilera 's son Max was her skeletal sidekick when the duo went trick-or-treating in L.A.'s tony Brentwood neighborhood.