Rihanna & Coco
Something tells us Tony the Tiger didn't have these two in mind when he declared, "They're grrrreat!" But Ice-T's mate (dressed appropriately as a porn star) and Ri-Ri look just that.
Katy Perry
The singer took the front hump of the camel—pal Shannon Woodward drove the rear—before giving up on the sweaty suit and promising via Twitter to be something a bit more "slutty" next year.
Kelly Killoren Bensimon
The Real Housewife of New York City channels a real German beer wench at Joonbug.com's 8th Annual Masquerade Ball.
Blake Lively
More pretzels, please! Something tells us the rest of the revelers at 1Oak would happily join the mile-high club with this Gossip Girl beauty.
Miley Cyrus
While some hand out Reese's Pieces on Halloween, Miley simply dispenses peace.
Michelle Trachtenberg
Mercy! This Marie Antoinette, who's fabulously halfway through her face-off with the guillotine, has her fortune read during the big bash at 1Oak in New York City.
Gwen Stefani, Gavin Rossdale, Kingston & Zuma
How cute are they? Only question: What is Gavin going as—a hot dad?
Paris Hilton & Doug Reinhardt
The heiress and her man give us two tutu-wearing tooth fairies for the price of one at Heidi Klum's bash at Voyeur in West Hollywood.
Nick Lachey & Vanessa Minnillo
Nick's Bel Air pad turned into a haunted mansion for Halloween, where he and Mrs. Stein reportedly showed guests a frightfully good time.
Kellan Lutz & Ashley Greene
The Twilight twosome blows off steam and an aristocratic 'tude at Tao's Halloween bash in Vegas at the Venetian.
Penn Badgley
This is how Gossip guys do birthdays on Halloween—with a gigantic Svedka vodka cake and a handlebar 'stache at 1Oak.
Holly Madison
The Girls Next Door star hosts a costume party at MGM Grand's Studio 54 nightclub, where at least one reveler was dressed as a pregnant Kendra!
AnnaLynne McCord
The 90210 star came as a caped crusader while hosting her sister's 21st birthday party at Tabú Ultra Lounge in Las Vegas.
La Toya Jackson
Looking like a space-age Eartha Kitt, La Toya totally wigs out as a B-52s wannabe at Millions of Milkshakes in WeHo. Just don't ask us if she brought all the boys to the yard.
Christina Aguilera & Max
A pair of pirates hit the streets of Brentwood to do a little trick-or-treating. It looks like Mama Pirate is giving the little one a stern lecture about music piracy (or something): Downloading unauthorized tracks is a trick, not a treat. They're never too young to learn right from wrong.
Mariah Carey & Nick Cannon
Mimi looks angelic and bountiful, making the scene seem downright heavenly at the All Hallows Eve bash at M2 club in NYC's Chelsea neighborhood.
Regis Philbin & Kelly Ripa
The Live stars don a handful of popular costumes, and Jon and Kate Gosselins will be everywhere this season!
Erik Estrada & Ryan Seacrest
The E! star's costume as Ponch from CHiPs is made all the more authentic when its actual star shows up in the studio. The whole thing was made even more ironic when Seacrest's alleged stalker was picked up in the E! lobby at the same time.
The Today Show
The plaza at 30 Rockefeller Center is tricked out with actual set pieces and costumes from Lucasfilm!
Mickey Rourke
The Wrestler star pays homage to Heath Ledger and dresses as the Joker for a party at Club Voyeur in Hollywood.
Rachael Ray & Rosie O'Donnell
This Wizard of Oz-themed photo might be the scariest of the bunch. Glinda, the good witch? Really?!
Charlie & Jerry O'Connell
When was the last time you saw a shark and killer whale this adorable? The brothers donned their swimsuits for a Camp Ronald McDonald Halloween Carnival.
Ellen DeGeneres
Halloween meets reality as the funnylady poses for as the cover of O magazine. "All I'm wearing under here is slacks and a smile," she says of her easy costume.
Tyra Banks
The supermodel struts her stuff as E!'s favorite voluptuous vixen, Kim Kardashian! Bonus points for the backpack placing her between Kourtney and Khloé.