Yesterday was Halloween, and Hollywood took advantage of the holiday with parties last night and all weekend long! There were plenty of elaborate costumes at bashes from NYC to Las Vegas, with Britney Spears and Jason Trawick posing with her dressed up sons in London. Jennifer Garner got witchy in LA, where pregnant Hilary Duff and her husband Mike Comrie donned their robber finest. Jessica Read more

We love seeing celebs go all out for Halloween, and naturally, it's even more fun for us to see them in costumes inspired by pop culture. Tons of stars dressed to the nines this year, so check out all of the costumes inspired by the entertainment world. From Harry Potter to Black Swan to one very awesome '90s throwback, check 'em out and tell us which one you like the best. Read more

Adults weren't the only ones having fun on Halloween! Many of Hollywood's most famous celebrity babies got in on the action, too, including Ali Larter and her fellow bumble Theodore. Amy Adams's adorable Aviana was a little cat, and Jessica Alba's Honor was Princess Jasmine from Aladdin. Katherine Heigl and Josh Kelley had a princess on their hands with Naleigh, and there were plenty more — Read more

Happy Halloween! The main event happened yesterday, but many stars got a head start on the fun over the weekend. We've seen lots of celebrity Halloween costumes from various parties and events, and the A-listers were also happy to share some of their own snaps online. We've collected photos from Brooklyn Decker, Nina Dobrev, Zac Efron, Jessica Alba, and many more — click through to see the Read more

The 90210 gang has hit plenty of parties since starting college, and Halloween is no exception. Not surprisingly, Naomi goes for a sexy costume, while Silver goes for a more unconventional look, dressing up as a hot dog. Take a look at what the rest of the party revelers decide to wear before tonight's episode airs! Photos courtesy of CW Read more

For our favorite Twitter celebrities, it was all about Halloween! Alessandra Ambrosio and Lea Michele both sported White Swan costumes while Jason Wu went the zombie route. Meanwhile, Whitney Port wore head-to-toe leopard print and Brooklyn Decker looked adorable as a giant duck. Click through to see 15 of our favorite fashionable tweeters in costume! Read more

Last night we saw some adorable (and creepy) costumes on celebrity couples celebrating Halloween. Many of the cute couples were attendees at Heidi Klum's annual Halloween bash, where every year she and hubby Seal go all out — remember Eve and the apple? — and this year was no exception! Can you spot the famous pair monkeying around? From gremlins to sailors to Disney royalty, see the cute Read more

Jessica Alba and Honor were in costume after attending a Halloween party in Santa Monica yesterday. Honor was dressed up as Princess Jasmine while Jessica painted her face like a cat and topped off her outfit with an Ella Moss fur vest. Honor switched into her homemade Bubble Guppies dress for trick-or-treating later that night and dad Cash Warren got in on the fun in a Superman suit. Baby Haven Read more

Halloween parties kicked off over the weekend and didn't wrap till the wee hours of this morning, drawing celebs from NYC to LA out for the festivities. Now that the holiday's officially over, you've got 364 days to start brainstorming next year's killer costume and we've rounded up our favorite celebrity costumes to help inspire. From the guests at Kate Hudson and Heidi Klum's Halloween bashes, Read more

Miranda Kerr gathered her Victoria's Secret ladies together last night for a Sexy Circus Halloween Party at NYC's Catch rooftop lounge. Her fellow Angels Chrissy Teigen and Kate Upton dressed up for the bash, as did former VS model Nicole Trufio and former America's Next Top Model winner Jaslene Gonzalez. One person who did not join in on the fun was Miranda's husband, Orlando Bloom, who joined Read more