An Overview of Conspiracy Theories
From shadowy government programs to satirical social movements, conspiracy theories have shaped public discourse for centuries. Below are 20 of the most well-known conspiracy theories, presented with estimated global believer counts, origins, and current status.
Inclusion on this page does not constitute endorsement. This is an informational overview for educational purposes only. Believer estimates are drawn from international polling data and may vary by source.
Claims that NASA faked the Apollo moon landings and that no human has ever walked on the lunar surface. Proponents cite anomalies in photographs and footage, all of which have been thoroughly explained by scientists and experts.
The belief that the Earth is a flat disc rather than a sphere, often claiming that space agencies worldwide conspire to fabricate evidence of a round Earth. Contradicted by millennia of scientific observation and evidence.
Alleges that the assassination of President John F. Kennedy in 1963 involved multiple gunmen and a broader conspiracy beyond lone gunman Lee Harvey Oswald. The 1979 House Select Committee on Assassinations concluded a probable conspiracy.
Claims that the September 11, 2001 attacks were orchestrated or deliberately allowed by elements within the U.S. government. Multiple independent investigations have confirmed the attacks were carried out by al-Qaeda.
Posits that a secret elite society, often called the Illuminati, covertly controls world governments, finance, and media to establish a unified authoritarian world government. The historical Bavarian Illuminati disbanded in 1785.
Claims that shape-shifting reptilian aliens have infiltrated positions of power worldwide, disguising themselves as political leaders, royalty, and celebrities to secretly control human civilization.
Alleges that the U.S. military recovered an alien spacecraft near Roswell, New Mexico in 1947 and that Area 51 houses extraterrestrial technology. The U.S. government acknowledged Area 51's existence in 2013 as a military test site.
Claims that the condensation trails left by aircraft are actually chemical or biological agents deliberately sprayed for purposes ranging from population control to weather manipulation. Scientists confirm these are ordinary water vapor contrails.
A sprawling conspiracy framework alleging that a secret cabal of elites engages in criminal activity and that a hidden insider known as "Q" has been leaking classified information. No claims have been substantiated.
Based on a fraudulent 1998 study that was later retracted, this theory falsely links childhood vaccines, particularly the MMR vaccine, to autism. Wakefield lost his medical license, and extensive research has found no connection.
A range of theories claiming that the COVID-19 pandemic was deliberately planned or engineered. While the lab leak hypothesis regarding viral origins has received serious scientific and governmental investigation, claims of intentional release remain unproven.
Proposes that the Earth is entirely hollow or contains a substantial interior space, sometimes said to house advanced civilizations or alien beings. Seismological data and our understanding of planetary physics conclusively disprove this claim.
Known as the "Paul is Dead" theory, it claims that Paul McCartney died in 1966 and was secretly replaced by a look-alike. Proponents cite supposed hidden messages in Beatles album art and songs played in reverse.
Claims that Elvis Presley faked his own death in 1977 to escape the pressures of fame and has been living in hiding. Fueled by reported sightings and alleged inconsistencies in official accounts of his death.
The belief in large, undiscovered primate-like creatures such as Bigfoot (Sasquatch), the Yeti, and similar cryptids around the world. Despite decades of reported sightings, no verifiable physical evidence has been produced.
Alleges that the 1997 car crash that killed Princess Diana was not an accident but a deliberate assassination orchestrated by the British establishment. Official inquiries in both the UK and France concluded it was a tragic accident.
Claims that a region in the western Atlantic Ocean is the site of an unusually high number of mysterious disappearances of ships and aircraft. Statistical analyses show the area has no more incidents than any comparable region of ocean.
Once dismissed as paranoia, MKUltra was a confirmed CIA program that conducted illegal experiments on human subjects to develop mind control techniques using drugs, hypnosis, and torture. Officially acknowledged through declassified documents in 1977.
Falsely claimed that a Washington, D.C. pizza restaurant was a front for a child trafficking ring involving political figures. The theory was thoroughly debunked but led to a real-world armed attack on the restaurant in December 2016.
A satirical conspiracy theory and social movement that humorously claims the U.S. government replaced all birds with surveillance drones. Created as a parody to highlight the absurdity of conspiracy thinking and misinformation.
Believer estimates are compiled from international polling and survey data, including Chapman University Survey of American Fears, YouGov international polls, Gallup surveys, PRRI American Values surveys, Pew Research Center global studies, Ipsos global polls, and various national and regional surveys. Global estimates are approximate and vary by methodology, sample size, and framing of questions. Where only regional data is available, figures are noted accordingly.