A letter supposedly written by the astrologers of Toledo and addressed to Pope Clement III began circulating throughout Europe in 1184. It predicted the end of the world would occur in September 1186. It said there would be wind and storms, drought and famine, pestilence and earthquake. The air would grow dark and a dreadful voice would be heard that would destroy the hearts of men. Coastal towns would be covered with sand and earth. All this would be triggered by a rare conjunction of the planets in the sign of the Scales and in the tail of the Dragon. People were advised to flee their homes and find safety in the mountains.

The letter caused panic throughout Europe. The Archbishop of Canterbury ordered a 3-day fast to prevent the calamity. When September 1186 arrived, the planetary conjunction did occur on schedule, but the end of the world never happened. Nevertheless, some attribute the Third Crusade of 1189 to the unrest stirred up by the letter.

This was not the end of the Toledo Letter. Variants of it continued to circulate for centuries, with names and dates altered. A version from around 1214, which attributed the text to a Cardinal Johannes Toletanus, warned of the end of the world in 1229, citing the same rare planetary conjunction as the reason. By the end of the fourteenth century the text was attributed to the Magisters in Paris, though the content of the warning remained essentially the same. Even as late as 1480 it was still in circulation, now attributed to a Mount Sinai hermit and a Rasis of Antiochia, who warned the end would come in 1510.

Michel de Notredame (1503-1566), better known as Nostradamus, rose to prominence as an astrologer in sixteenth-century France. He was supported by the patronage of Queen Catherine de Médici, for whom he wrote numerous verses implying the downfall of her rival, Elizabeth I of England. Obviously, these predictions did not come true. His most popular work was The Prophecies, first published in 1555, which has remained in print to this day.

Nostradamus himself cannot properly be regarded as a hoaxer since astrology in his time was a highly respected practice. He believed in the legitimacy of his art. The real deception lies in the uses to which his work has been put since his death.

Nostradamus wrote his prophecies in an ancient form of French worded so ambiguously that it could be interpreted to mean almost anything a reader desired. As a result, his followers have been able to credit him with predicting a wide range of calamities including the great London fire of 1666, the rise of Adolf Hitler, the Iranian revolution of 1979, and the events of September 11, 2001. However, Nostradamus's supposed predictions are only ever noted after the fact. There has never been an instance in which a verse by Nostradamus has been used to accurately predict an event before it occurred.

The work of Nostradamus has also been a theme in a large number of outright hoaxes—instances in which verses were falsely attributed to him. For instance, during World War II the Nazis spread propaganda claiming that Nostradamus had prophesied the success of Hitler. The Allied countries retaliated by spreading propaganda claiming Nostradamus had foreseen Germany's defeat. After 9/11 interest in Nostradamus surged thanks to some verses of his, circulated by email, in which he seemed to predict the tragedy. However, the verses had not actually been written by him. They were the work of an anonymous hoaxer.

In 1812 a Philadelphia man, Charles Redheffer, claimed to have invented a perpetual motion machine that required no source of energy to run. He built a working model of the machine and applied for funds from the city government to build a larger version. But when inspectors from the city examined it, they realized that Redheffer had simply hidden the power source. To expose Redheffer, they commissioned a local engineer to build a similar machine, and when they showed this to Redheffer he fled the city. (This replica is still owned by the Franklin Institute in Philadelphia.)

A year later, Redheffer attempted the same scam in New York City. This time he was exposed by the engineer Robert Fulton who is said to have removed some boards from a wall neighboring the machine, exposing the source of the machine's power: an old bearded man sitting and eating a crust of bread with one hand, while he turned a hand-crank with the other. More→

Ancient Scottish legend told of a "beast" that lived in the waters of Loch Ness. St. Columba, for instance, was supposed to have encountered a large serpent in the River Ness over 1400 years ago. But the modern history of Nessie began in 1933 when a new road was completed along the northern shore of the Loch, providing easy access to unobstructed views of the water. Soon after this, a couple spotted an "enormous animal" in the Loch. The Inverness Courier wrote up their sighting, describing what they saw as a "monster;" intense media interest followed; and thus was born the modern Loch Ness Monster. More→

In 1968 Carlos Castaneda, a graduate student in anthropology at the University of California at Los Angeles (UCLA), published The Teachings of Don Juan: A Yaqui Way of Knowledge. It described his encounters with Don Juan Matus, a Yaqui shaman from Mexico. Don Juan supposedly trained Castaneda in ancient forms of knowledge, such as how to use drugs to communicate with animals (or even to become an animal). Castaneda's book became a bestseller and was an important influence on the New Age movement. Castaneda was awarded a doctorate by UCLA in 1972.

Castaneda insisted Don Juan was a real person, but this is widely doubted by scholars. Skeptics point to the fact that Castaneda never describes Don Juan speaking in his native language, nor does Don Juan use local names to describe any plants or animals. Castaneda never showed his field notes to anyone. And many of the experiences Castaneda describes, such as hiking for days through the Sonoran desert in the middle of the summer, border on the impossible.

Castaneda also falsified details of his own biography. Castaneda claimed he was born in Brazil in 1935, but an investigation by Time magazine revealed he was actually born in Peru in 1925.

Chariots of the Gods?, written by Erich von Däniken, was first published in 1968. It became an international bestseller. The thesis of the book is that ancient human civilizations had contact with visitors from outer space. These "ancient astronauts" were supposedly responsible for many of the great architectural feats of history, such as the Egyptian pyramids, the Nazca lines of Peru, and the statues on Easter Island.

Mainstream archaeologists dismiss von Däniken's argument as pseudoscience. A charitable view of von Däniken would credit him with really believing all the arguments he makes. A more cynical view paints him as a knowing hoaxer. For instance, one of his central arguments is that it would have been impossible for past civilizations to build monuments such as the pyramids. But von Daniken refuses to consider contradictory evidence. In fact, many theories adequately explain how these monuments could have been built by early civilizations with the technology of the time.

Von Däniken also invents facts. In a follow-up book, The Gold of the Gods, he described visiting the "Caves of Gold" located beneath the jungles of Ecuador, where the treasure of the Incas is supposedly hidden. Here he saw a vast library of metal books containing the writings of the ancient astronauts. However, von Däniken was not willing to disclose the location of these Caves of Gold. There is no evidence they exist outside of his imagination.

Frank Searle, a former army captain, arrived in Loch Ness to search for the monster during the early 1970s and soon established a reputation as a definite character. He was like a colonial-style adventurer, assisted by a succession of attractive young "monster huntresses." He took an enormous number of photos of Nessie, many of which were published by the media, but all of which have been dismissed by experts as fakes. His early photos, such as the one to the right (taken in October 1972) have been identified as pictures of floating tree trunks. In later photos he progressed to cutting-and-pasting dinosaurs from postcards into his images. Searle left the loch in 1985 and died in 2005.

August 7, 1972: An expedition to find Nessie led by Dr. Robert Rines of the Academy of Applied Science struck gold when its underwater camera took a picture of what appeared to be the flipper of a large aquatic animal resembling a plesiosaur. However, the relatively clear image of a flipper shown to the public was not quite what the camera had initially recorded. The initial image was far less distinct. (It basically looked like a shot of a bunch of bubbles or sediment in the water.) This initial picture was then computer enhanced by the NASA Jet Propulsion Laboratories in Pasadena, and apparently the computer-enhanced image was further artistically enhanced by the Academy of Applied Science team (i.e. it was retouched), thereby producing the final flipper photo. Modern image-enhancement software has not been able to conjure anything resembling a flipper from the original image.