Katy and her BFF Shannon Woodward channeled MTV's '90s cartoon Daria (Katy tweeted the above pic before the party), while Rob and Kristen donned their usual garb -- jeans and t-shirts -- but threw on Halloween masks to get in the spirit, as documented in photographs taken at the party.
In celeb costume highlights according to a partygoer, recent Emmy winner Aaron Paul dressed as Max from Where the Wild Things Are, while comedians Craig Robinson and Aziz Ansari went as a superhero and a Thomas the Tank engine-esque train, respectively. Abbie Cornish donned a Morticia Addams-esque black dress and black wig with dramatic pale makeup and red lips to match, while Rose McGowan dressed as an ice queen, and Maroon 5 bass player Mickey Madden bore an uncanny resemblance in his costume of dubstep DJ and producer Skrillex. Ricky Gervais pal Stephen Merchant dressed as a king, while former United States of Tara star Brie Larson wore a Lucille Ball-esque get-up. Others at the party included Captain America star Chris Evans, Radiohead frontman Thom Yorke, comedian Jamie Kennedy, and of course, the other members of Maroon 5.
The down-to-earth, festive atmosphere left no room for egos, with stars sidling up to the bar to order their own drinks, and even in one instance politely indulging the bartender's request for a photo.
The creepy bash recalled Maroon 5 frontman Adam Levine's recent stint on American Horror Story, taking place half inside a mausoleum, and half outdoors at Hollywood Forever Cemetery -- the final resting place of stars including Rudolph Valentino, Douglas Fairbacks and Dee Dee and Johnny Ramone. The carnival-themed party was sponsored by Patron tequila, and featured several tequila stations, an In-N-Out burger truck, a hot dog truck, a Coffee Bean and Tea Leaf coffee bar, popcorn and cotton candy stands, a Patron photo set-up, and carnival games including skee ball and a Patron ring toss. (The prize was sadly not a bottle of Patron, but a stuffed animal.)
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