Have You Picked Out Your Halloween Costume Yet???

October 31st is the BEST day of the year! Why? Because you get to dress up like somebody else! Hollywood actors are already used to that - after all, it's their job! Halloween '08 was pretty fab... Courtenay Semel did her best Amy Winehouse impression, a pre-married Khloe donned a police officer's outfit and Mariah Carey dressed up like a sexy (what else?) firewoman! But our fave costume from last year? Heidi Klum went all out! And we loved it. So before you do your last-minute shopping for Halloween tomorrow, check out our MONSTER gallery below of celebs in their best costumes ever! Happy Halloween!