It's that time again! Some of the biggest names in Hollywood stepped out to celebrate Halloween 2013, dressed as film characters, other A-listers, comic superheroes and much more! Check out some stars -- including Hilary Duff, Vanessa Hudgens and John Stamos -- who went the extra mile to get decked out for some of the biggest Halloween parties of the season.
Where's Bonnie? Jeremy Piven dressed up as old-timey gangster Clyde for Treats Magazine's 3rd Annual Trick or Treats Halloween Party in Los Angeles on Oct. 31, 2013.