A hoax is a deliberately fabricated falsehood made to masquerade as truth. It is 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.

More information on the Wikipedia pages Literary hoax, Hoax and List of Hoaxes which has a long list of examples.

The Voynich Manuscript is considered by some to be a hoax.

See also literary forgery.