Percentage of Americans: 4%
Who believes it: Author of The Biggest Secret, David Icke

According to this theory, a cold blooded, flesh eating, shape shifting, reptilian/ human elite live among us and take the form of politicians and socialites, including Queen Elizabeth, Henry Kissinger, and Bill and Hillary Clinton. Aside from being associated with secret societies like the Freemasons and the Illuminati, this reptilian race is only out for one goal in mind: to enslave humankind. But what's most unbelievable is just how people subscribe to this theory. For that, we have David Icke to blame, who became the poster man for divulging "America's biggest secret" in his first book, unsurprisingly named The Biggest Secret.