Close this search box.

6 Most Popular Conspiracy Theories in History

What are the most popular conspiracy theories ever believed?

Conspiracy theory: Just saying these words in public can make people politely back away, looking for someone who won’t corner them with wild views about how Elvis and Bigfoot are cryogenically frozen in an underground bunker.

From a faked moon landing to crazy ideas about JFK’s assassination, and conspiracy theories, there’s no shortage of believers.

And thanks to social media, the public is pushed toward ever-more-emotional, conspiratorial content, which makes it easier for the most popular conspiracy theories to circulate.

They all must have certain necessary elements: a conspiracy between two or more people, a secret action, and a motive, according to a social psychology professor. Why are they so fascinating?

According to experts, it could be the social need to know the truth and have certainty, the existential necessity to feel safe, or a sense of control over what happens to us.

And true believers are experts at rationalizing away evidence that conflicts with their beliefs. Below, Science In The World looks at 6 of the most popular conspiracy theories of our past.

Let us know in the comments if we left any out!

Most Popular Conspiracy Theories
Photo by mark reinstein at Shutterstock

Princess Diana’s Death

Within hours of Princess Diana’s death on August 31st, 1997, in a Paris highway tunnel, conspiracy theories began swirling. The idea that such a beloved and high-profile figure could be suddenly gone was a huge shock.

This was especially true of Princess Diana: We’re conditioned to believe that royalty dies of old age, political intrigue, or overeating rich food. They don’t just get killed by an everyday drunk driver.

Unlike most popular conspiracy theories, though, this one had a billionaire supporting it. Mohamed Al-Fayed, the father of the man who died in the crash with Diana, claims that the accident was an assassination by British intelligence agencies at the demand of the Royal Family.

Al-Fayed’s declarations were examined and dismissed by a 2006 inquiry. On April 7th, 2008, the coroner’s jury reported that Princess Diana and Al-Fayed were unlawfully killed due to carelessness by their drunken chauffeur and pursuing paparazzi.

Prince Harry also believed this conspiracy theory. In January 2023, he said he thought she could still be alive for “many years” after the crash. He told Anderson Cooper on “60 Minutes” that he thought she might have faked her death and they would be reunited at some point.

The Holocaust

During World War II, over six million Jews were massacred across Europe in a horrendous genocide led by dictator Adolf Hitler.

Even though the Holocaust is one of the most-documented events in history, a big chunk of the population either doesn’t believe it happened or thinks the death toll has been significantly inflated.

A survey done in 2014 of over 53,000 people from 100 countries found that only 30% of respondents thought historical reports of the Holocaust were accurate.

Interestingly, those under 65 were likelier to say they didn’t believe the Holocaust happened as history books tell it did. Poor education on the topic could be an explanation for this conspiracy theory.

Still, some conspiracy theorists push the anti-Semitic notion that the Holocaust was devised or exaggerated to earn sympathy and economic gains for Jewish people while advancing Jewish interests.

Historians have separated Holocaust deniers into two groups: There are the hard-core nay-sayers who say the Holocaust didn’t happen at all. And there are the less-fervent deniers who admit the Holocaust happened but doubt the official death toll or that gas chambers were utilized for mass murder.

One question from historian Deborah E. Lipstadt remains: “For the deniers to be right, who has to be wrong? Well, clearly all the survivors… the bystanders. But mostly, you have the perpetrators. They never said it didn’t happen.”

Did the CIA create AIDS?

It’s obviously human nature to look for someone to blame in terrible situations. The HIV/AIDS crisis was just one of those moments in our history.

To this day, one of the most popular conspiracy theories is that the CIA invented the virus deliberately to attack African-American and homosexual communities.

Even though this conspiracy theory isn’t true, it does possess links to a real disinformation campaign propagated by the Soviet Union in the 80s known as Operation “INFEKTION.”

The purpose was to implicate the United States of America as a supplier of biowarfare by declaring they developed HIV/AIDS in Fort Detrick, Maryland.

Today, Operation “INFEKTION” is mainly seen as a way to deflect similar charges against the USSR over their biowarfare operations.

Most Popular Conspiracy Theories
Photo by Castleski at Shutterstock

The Moon Landing

In 1969, NASA landed astronauts on the moon. By the 1970s, a bizarre ruse materialized that the moon landing never happened. This conspiracy theory was described in a 1976 book: “We Never Went to the Moon: America’s Thirty Billion Dollar Swindle,” and a 1978 movie, “Capricorn One.”

Even as late as 2001, a Fox documentary, “Conspiracy Theory: Did We Land on the Moon?” suggested that the Apollo moon-landing program was falsified. There are many debunkings of the myriad of moon scam claims.

And then there’s the matter of the many pounds of moon rocks that have been analyzed worldwide and confirmed as being of extraterrestrial origin. So how could NASA get the stones, if not during a moon landing?

Why would scientists from around the globe willingly participate in the American space agency’s hoax? This one truly is one of the most popular conspiracy theories out there. Many astronauts have been offended by this implication that they fabricated their accomplishments.

In fact, when conspiracy theorist Bart Sibrel encountered Buzz Aldrin in 2002 and told him he was a “coward and a liar” for pretending about the moon landings, the then 72-year-old punched Sibrel in the face.

Did the CIA have a hand in JFK’s assassination?

Lee Harvey Oswald was arrested on November 22nd, 1963, for killing President John F. Kennedy Jr. in Dallas, Texas. Two days later, while transported to a local jail, Oswald was killed by a man named Jack Ruby.

This startling set of events was a perfect setting for conspiracy theories from the beginning. Not only was a popular president fatally shot in the middle of the day, the accused killer was taken out days later, inviting speculation about a cover-up.

As early as the late 60s, over half of the American public didn’t believe Oswald acted by himself. And as of 2017, 61% of Americans believed the assassination involved a conspiracy. There are actually quite a few main JFK conspiracy theories.

One popular view is that the CIA killed JFK in retribution for the failed Bay of Pigs invasion to defeat Cuban leader Fidel Castro.

According to biographer Philip Shenon, Bobby Kennedy and the attorney general first believed that a group of CIA agents who went rogue were involved in JFK’s death. However, he later rethought this idea. Another conspiracy theory is that Oswald wasn’t the lone gunman.

People can hardly be criticized for believing this when a House of Reps Select Committee on Assassinations found that there was “probably” a second shooter involved. In 1982, another committee questioned those results. But the theory had already taken root.

And you might have heard about this third theory: The assassination was a mob hit meant to punish Bobby Kennedy for trying to get rid of the mafia.

If you’re as fascinated by the most popular conspiracy theories out there as we are, we think you’ll enjoy this book from Amazon: The Mammoth Book of Cover-Ups: The 100 Most Terrifying Conspiracies of All Time 

Most Popular Conspiracy Theories
Photo by Melnikov Dmitriy at Shutterstock

Population control using COVID-19.

There are many conspiracy theories about coronavirus: The vaccine is actually a microchip implanted in people to track them. Then there’s the one about the fatality rate, that has been wildly inflated.

Our favorite conspiracy theory might be about how Bill Gates is responsible for the virus and the head of a plot to use the virus as population control. Have you grown bored yet?

Let’s set the record straight! …These conspiracy theories have been debunked many times, yet they prevail.

This may have something to do with our old president Donald Trump saying the virus was no more deadly than the common flu and would one day simply “disappear, like a miracle” without the necessity for a vaccine.

Or it could be connected to some Republican lawmakers who threw out the idea that COVID could be a Chinese “bioweapon.”

But in all honesty, many believe that in a time of historic political polarization, this country wasn’t suited to deal with a catastrophic pandemic that killed thousands of Americans nationwide!

What do you think about the most popular conspiracy theories? Be sure to share your thought with our readers in the comments section below.

Meanwhile, if you liked this post, we think you’ll also get a kick out of this: Vacuums, Telephones, and 6 Other Things Invented in People’s Garages


Leave a Reply

Your email address will not be published. Required fields are marked *

Related Posts