The Cardiff Giant: In 1869 a man named George Hull spent nearly $3,000 to carve, ship and "discover" a petrified giant, then turned it into a sideshow attraction. It was so popular that P.T. Barnum created his own copy of the creature and claimed that Hull's was a fake. A resulting lawsuit over which giant was "real" revealed that both were frauds.

The Feejee Mermaid: There are many versions of this hoax, but the most famous is attributed to P.T. Barnum, who leased the creature for his sideshow as part of an agreement with its creator, Moses Kimball. In reality, it's just the torso and head of a baby monkey sewn to the back end of a fish.

The Furry Trout: The tall tale that fish in North America grow fur to keep warm goes back centuries, but in reality it's just the result of a fungal infection that causes a cottony substance to grow on fish, which then wash up dead on shore. At some point people starting faking their own, and they're in curiosity museums all over the world today.

The Martian Monkey: In 1953, two Atlanta barbers removed the tail and all the hair from a dead rhesus monkey, covered it in green food coloring and left it in the middle of the road for police to find. They then told the cops that they'd seen the creatures all over town. The "Martian Monkey" caused panic for a few hours, until an anatomist identified the creature as an ordinary monkey. The hoaxers had to pay a $40 fine for obstructing the roadway.

The Giant Penguin: In 1948, several people reported finding giant, three-toed footprints on Florida's Clearwater Beach. This led to several sightings of a giant penguin in the area and the birth of a local legend. Four decades later, a local prankster came forward and claimed he and a now-dead friend made the tracks using large iron castings.

The Hodag: In 1893 a Wisconsin man named Eugene Shepard reported to have captured and killed a beast with "the head of a frog, the grinning face of a giant elephant, thick short legs set off by huge claws, the back of a dinosaur, and a long tail with spears at the end." He claimed to have caught another such creature alive three years later, but when the Smithsonian wanted to come and study it, Shepard was forced to admit the hoax.

The Jenny Haniver: These creatures can look like angels, demons, dragons and even aliens, but they're really just the dried, carved bodies of rays, often coated in varnish. Sailors have been using this trick to sell curiosities for centuries.

The Lake George Monster: In 1904, painter Harry Watrous decided to out-prank a man who'd placed a large wooden fish in Lake George, so he carved and painted a sea monster head on top of a log and anchored it out on the water. The prank ignited a local legend. Watrous eventually came clean, and the monster head is now a museum piece.

The Panama Creature: In 2009 a group of teenagers claimed to have killed a strange creature that attacked them while they were playing near a cave in Panama. They later took photos of the creature and sent them to a local news agency. Speculation about what the creature could be was rampant, until a necropsy revealed that it was a sloth that had lost all its hair due to underwater decomposition.

The Pacific Northwest Tree Octopus: Created as an internet hoax by Lyle Zapato in 1998, the tree octopus is a rather tongue-in-cheek fraudulent creature. The website that gave birth to it, though, is still used to teach students internet literacy, and many of them don't realize it's a fake.

The Skvader: The Skvader is based on an old Swedish folk tale. No one's ever exactly tried to prove it's real, but in 1918 taxidermist Rudolf Granberg built one, and it's been delighting visitors to Sweden's Ornskoldsvik museum ever since.

Pickled Dragon: In 2003 David Hart claimed to have found the fetus of a dragon preserved in a jar in his garage in England. He even claimed he had papers that dated the specimen back to the 19th century. The dragon was actually a model originally made for the TV series Walking with Dinosaurs, and the hoax was used as a publicity stunt to promote Hart's novel.

Modern Day Diplocaulus: When these photos started circulating on the internet a few years back, a biologist claimed the creature couldn't possibly be real, as it had been extinct for 270 million years. The creature was eventually revealed to be the work of a Japanese model artist.

The Little Blue Man: In 1958, several people driving along a certain Michigan road reported seeing a glowing blue man appear out of nowhere and then disappear. Sightings went on for weeks before three young men came forward and confessed they'd made a suit and spray-painted it glow in the dark blue as a UFO-themed prank. They were let off with a warning.

The Flipper Photo: When a 1972 expedition to Loch Ness came back with this underwater photo, the world took notice, but skeptics quickly poked holes in the image. The "flipper photo" is the result of re-touching. The original image is far less distinct.

Bigfoot Tracks: In 1958, a California construction worker named Jerry Crew arrived at work to find a series of massive 16-inch footprints in the mud. The media began referring to the creature that must have made the tracks as "Bigfoot," and the name stuck. The source of the tracks was eventually revealed to be Crew's prankster boss, who made them using carved wooden feet that he strapped onto the bottoms of his shoes.