Percentage of Americans: 14%
Who believes it: Thabo Mbeki, South African President; Wangari Maathai, Nobel Peace Prize winner and ecologist

This wasn't (and wouldn't be the first time) the CIA would be allegedly involved in harming American citizens. In the late '70s and early '80s, rumors began circulating that the CIA created the virus AIDS to eliminate homosexuals and African Americans and that in gay friendly cities such as New York, Los Angeles, and San Francisco, a number of clinics were injecting gay men with the fatal virus. Incredibly, the insane conspiracy has stood the test of time, as a number of prominent figures have supported the theory, including Nobel Peace Prize winner Wangari Maathai.