Conspiracy. Just saying the word in conversation can make people politely edge away, looking for someone who won’t corner them with wild theories about how Elvis, John F. Kennedy, and Bigfoot are cryogenically frozen in an underground bunker.

Yet conspiracies do exist. In the corporate world, major companies we buy products from everyday have been found guilty of conspiring to fix prices and reduce competition. Just about any planned criminal act committed by more than one person could be considered a conspiracy, from simple murder-for-hire to the Watergate break-in.

Many conspiracy theorists go much further, though, and see a hidden hand behind the world’s major events. While some of the theories have a grain of truth to them, conspiracy theories are impossible to disprove, because the hardcore believers will find some way to rationalize away evidence that contradicts their beliefs. Eyewitnesses who dispute their conclusions are mistaken—or part of the conspiracy.

At least that's what they want you to think ...

Top Ten Conspiracy Theories