...And they even wore some pretty imaginative costumes!

Last night, Hollywood's A-listers got in the Halloween spirit as they all attended Kate Hudson's annual bash in Pacific Palisades.

From Fergie as Elvira and Josh Duhamel as a spooky tuxedo'd ghoul, Jessica Alba dressed as who-knows-who (Cher in pajamas?) to Bradley Cooper as a gorilla in a furry one-piece with girlfriend Suki Waterhouse on the back of his bike, no one seemed to show up sans costume to huge shindig.

Click through the pics to see everyone's outfits!