It's a holiday where you can be anything you want. So when you're already a celebrity, the costume decision can be that much more difficult.
Now that Halloween is over, we look at what celebrities were for the holiday and see who won Halloween and who just failed to impress.
Starting off this year's winners: Heidi Klum never disappoints. She was a butterfly this year, but this may just be the most elaborate butterfly costume of all time.
The model and Project Runway host paid attention to detail and went all out with the makeup and bug eyes.
Next up, Katy Perry did not just use flaming hot Cheetos in her music video for Dark Horse -- she transformed into a flaming hot Cheeto! (And it looks like cheesiest, most hilarious costume yet.) Her matching Cheetos purse made this junk food look even more appealing.
Fashionista Lauren Conrad also got creative this year in DIY fashion. She was a mermaid with real mixed seashells including tiny starfish, and the best part about her costume was that she explained how to make on her blog.
Making this year a family affair, actor Neil Patrick Harris and his family went all out too and went as DC Comics characters from Gotham City. This family could not be any more adorable.
Also making her Halloween a family affair, reality star Kim Kardashian dressed up as Vogue's Editor-in-Chief Anna Wintour with her baby North West as Vogue's contributing editor Andre Leon Talley.
When Kim was featured on Vogue's cover with her husband Kanye West, there was a lot of backlash about whether the reality star deserved the be on the legendary high-fashion magazine cover. At the time, Talley defended the magazine's decision. Now, Kim is showing her appreciation for the magazine duo.
Rounding off the top 6, Beyonce takes the cake with Blue Ivy as they dressed up as another musical family. Dressed as Janet and Michael Jackson, the mother and daughter honored the Jackson family.
The costumes can't be all great though. We expected a little more from these celebs.
For our worst list, we start out with Paris Hilton.
The heiress dressed as a pomeranian and posed in front of her shoe closet, and her shoes look way more impressive than the actual costume.
Actor Jason Biggs also did not inspire with this carrot costume. If he did not say it in the caption, we're not sure we would have ever been able to guess.
While Kim and North made a great Vogue magazine power team, Kim's first skeleton costume of the day lacked the creativity she later had. While the makeup is well done, the skeleton was not her best costume idea.
While we love the Power Rangers, we expected more from singer Justin Bieber this year. This costume is one of the most overdone.
And while they may actually make the best couple's costume, it's one of the worst at the same time as The Big Bang Theory's Kaley Cuoco dresses up as Justin Bieber, and her husband Ryan Sweeting played the part of his on and off-again girlfriend Selena Gomez.
Hugh Grant may just have had the worst costume this year though as the actor failed to wow when he put on this strange horse mask for the UNICEF Halloween ball.
Which celeb Halloween costume was your favorite or least favorite? Let us know using #ETnow.