Christina Aguilera plays "doctor and nurse" with then-fiance Jordan Bratman at their Halloween party at The Hard Rock Hotel and Casino in Las Vegas on Oct. 29, 2005.
Adam Levine and Anne V recreate November Rain at the 2011 Maroon 5 Halloween Party in Los Angeles.
Skrillex performs as part of the 2012 Voodoo Music Experience at City Park on October 28, 2012 in New Orleans, Louisiana.
Christina Milian celebrates the launch of her custom halloween cocktail recipe for HPNOTIQ Liqueur at Beacher's Madhouse on October 26, 2012 in Hollywood, California.
Beyonce slings her web as Spider-WoMan.
Stevie Wonder, in a skelton-friendly black ensemble, and Bette Midler, wreathed in black lace and roses, posed together at Midler's New York Restoration Project's Hulaween in New York City, last October.
Zac Efron is ultra-serious as a retro cop with a big gun as he poses with duo Aly & AJ, both in racy costumes.
The ever colorful LMFAO shows off their muscles (and feathers) as wrestling heroes on October 30, 2011.
Despite being seemingly dead, Heidi Klum enjoys the 2011 bash with Roots' drummer, Questlove.
Bee and Bunny - Bebe Rexha and Pete Wentz of Black Cards pose backstage at Good Units 2011 Halloween bash.
Fergie announces her 'Universal Royalty' at Heidi Klum's annual Halloween party in New York.
A preganant Bee-yonce and Mike-ye Wackson attend a party at The Darby in New York, 2011.
Darren Criss and his smirk proudly show off his as Robin costume on the set of a "Glee" episode this year.
Red-eyed vampire Katy Perry and John Mayer and his gory head on a stick stare eerily for the cameras at her birthday/Halloween party in Los Angeles.
Natasha Bedingfield at Heidi Klum's annual Halloween party in New York.