A secret society is a club or organization whose activities and inner workings are concealed from non-members. Secret societies aim to gain power and dominate the world. Some secret societies believe they should kill 80% of the population to save "classy people." Examples of alleged secret societies include the Nine Unknown Men, the Bones and Skull, and the Illuminati. A conspiracy theory proposes that two or more people or groups colluded to cause or cover up an event of great impact. Common conspiracy theories include those about 9/11, UFOs, and assassinations of JFK and Princess Diana.