Halloween: The one day a year you get to dress up as anything you want (slutty Betty White, here we come!). And if you’re a Hollywood star, you’ve got access to all the costumery and makeup in the world. Still, with all those choices, what do some celebs choose to trick-or-treat as? Other celebs, of course! And the ouroboros of Hollywood has never looked so spooky. From Hilary Duff as g>Angelina Jolie to Perez Hilton as Lady Gaga, we’ve got a gallery of our favorite celebrities dressed up as other celebrities.