Debra Messing dresses as Marie Antoinette


Paris Hilton and boyfriend River Viiperi dress as Robin and Batman


Calista Flockhart and Harrison Ford dress as nerds


Chloe Moretz as a ghoul


Jessica Simpson dresses as a wench, Eric Johnson as Braveheart and Maxwell Drew as a rooster


Jennifer Nettles dresses as a pumpkin smuggler


Mark Salling dresses as Ned Flanders


Ginnifer Goodwin dresses as Rosemary's Baby


Marie Osmond dresses as Lucille Ball


Miley Cyrus dresses as Nicki Minaj


Ellen DeGeneres dresses as Sofia Vergara


Ricki Lake as Cher


"The Talk" dresses as the cast of "Alice in Wonderland"


Lance Bass, Matthew Morrison and JC Chasez


Chord Overstreet, Harry Shum Jr. and Matthew Morrison


Kyle Howard


Darren Criss


Dianna Agron


Shenae Grimes, dressed as Monster High's Frankie Stein, and boyfriend, Josh Beech


Cassie as Cleopatra and Diddy as Prince


Pete Wentz and Meagan Camper dress as a beauty queen and her daddy


Patrick Schwarzenegger &Aly Michalka


Kendra Wilkinson gets her referee


Fergie


Christina Milian dressed like the Queen of Hearts


Alexa Vega


Jessica Alba, Cash Warren and Honor as The Incredibles.


Nicole Richie (right) and friends as Troop Beverly Hills


Lucy Hale as My Little Pony.


Lauren Conrad


Troian Bellasario as The Girl with the Dragon Tattoo.


Hilary Duff


Emma Roberts and Evan Peters


Ariel Winter


Amandla Stenberg dresses up like a vampire