Hoaxes That Fooled The World

A hoax is a deliberately fabricated falsehood made to masquerade as truth. It's distinguishable from errors in observation or judgment, or rumors, urban legends, pseudosciences or April Fools' Day events that are passed along in good faith by believers or as jokes.

There have always been hoaxes (even before the Internet), and we've all fallen for them at one time or another.