The Hoax Archive
Got some time to kill and an internet connection? You've got hoaxes! The Hoax Archive (aka Museum of Hoaxes) catalogues historical hoaxes by both date and category. Some favorite categories of mine: Travel and Exploration Hoaxes; Extraterrestrial Life Hoaxes; and April Fool's Day Hoaxes. Here's a summary of the Patagonian Giants hoax (categorized as a "rumor"):
In 1766, when the Dolphin returned to London after circumnavigating the globe, a rumor began to circulate alleging that the crew of the ship had discovered a race of nine-foot-tall giants living in Patagonia, South America.
In fact, the rumor of South American giants had a long history, dating as far back as the 1520s. According to this rumor, the name Patagonia actually meant "land of the big feet".
In reality, there were no South American giants, and Patagonia didn't mean "land of the big feet". When the captain of the Dolphin published his official account of the voyage in 1773, he revealed that his crew had indeed encountered a tribe of Patagonians, but that the tallest among them had measured only 6 feet 6 inches. In other words, the Patagonians were tall, but they weren't giants.
Photo shown above (from Wikipedia): "1840s (fanciful) illustration of a Patagon chief from near the Straits of Magellan, bedecked in costume of war." There's more on the whole Patagonian Giants if you're interested, including a citation for the story. My favorite part of this Hoax Archive site, honestly, is that it actually cites sources -- now, whether those citations are accurate is up to you to track down....
See also: Patagon, the Wikipedia entry on the Patagonian Giants.
(Public domain photo from Wikimedia Commons; cropped.)