Discordianism is a religion, philosophy, or paradigm centered on Eris, also known as Discordia, the Goddess of strife and discord. Discordianism uses archetypes or ideals associated with her. It was founded after the 1963 publication of its "holy book," the Principia Discordia, written by Greg Hill with Kerry Wendell Thornley, the two working under the pseudonyms Malaclypse the Younger and Omar Khayyam Ravenhurst.

The religion has been likened to Zen based on similarities with absurdist interpretations of the Rinzai school, as well as Taoist philosophy. 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 is any more accurate or objectively true than the other.

There is some discord as to whether Discordianism should be regarded as a parody religion, and if so, to what degree. 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.