Trick Or Treat : Celebrity Halloween Costumes – That Is Celebrities Wearing Halloween Costumes . Everyone loves Halloween, even celebrities. It’s the only time dressing up and pretending to be someone else, besides a movie roll, is appropriate. As this year’s Halloween approaches, I’ll post more pics of celebs in their costumes, both for now, I’ll be posting about previous years. From Kim K as poison Ivy ( love her in this, can’t wait to see what she does this year) to Pink as a clown. Look below to see celebrities wearing Halloween costumes, lets see if you can figure out who they are.