Celebrities rarely need an excuse to let their inner freak out, so come Halloween night, Hollywood turns into one huge psychiatric ward for the rich and famous. Without further ado, here are a few celebrities who were possessed by the Halloween spirit.

Above we have “How I Met Your Mother” star, Neil Patrick Harris, as a Killer Clown.

Below are Teri Hatcher and daughter Emerson as The Queen of Hearts and Alice, followed by Mario Lopez naked. Actually, he’s supposed to be a warrior of some sort, but the photographer was clearly fixated by Marios’ back side.

Above is Dennis Rodman dressed as…well, Dennis Rodman, followed by Paris Hilton as an Alice in Wonderland/Marilyn Manson/cheap hooker (surprise, surprise!) hybrid. And finally, below are reality show star Brody Jenner and friend Frankie Delgado as Batman and Robin. Someone forgot to tell these two that a super hero’s best-kept secret weapon is an athletic supporter.

Click on any of the pics for a larger view.