Discordianism is a religion based on the worship of Eris (also known as Discordia), the Greco-Roman goddess of chaos. It was founded circa 1958–1959 after the publication of its (first) holy book the Principia Discordia, written by Malaclypse the Younger and Omar Khayyam Ravenhurst after a series of shared hallucinations at a bowling alley.

The religion has been likened to Zen, based on similarities with absurdist interpretations of the Rinzai school. Discordianism is centered on the idea that both order and disorder are illusions imposed on the universe by the human nervous system, and that neither of these illusions of apparent order and disorder are any more accurate or objectively true than the other.

There is some division as to whether it should be regarded as a parody religion, and if so to what degree. Discordians use subversive humor to spread their philosophy and to prevent their beliefs from becoming dogmatic. It is difficult to estimate the number of Discordians because they are not required to hold Discordianism as their only belief system, and because there is an encouragement to form schisms and cabals.