(12 of 15) Celebrities in Halloween CostumesIt’s that time of year again, when celebrities strut their stuff before a plentitude of paparazzi, dress up in the latest couture costume, and show their enthusiasm for the most anticipated event of the season. Check out stars like Heidi Klum, Paris Hilton, and Diddy—dressed to kill in the spookiest, sexiest, and craziest getups for Halloween. Zac Posen Posen arrives at Heidi Klum’s Halloween Party at Happy Valley nightclub in New York City as the devil incarnate on Oct. 31, 2005.