The Illuminati is a name given to several groups, both real and fictitious. Historically, the name usually refers to the Bavarian Illuminati, an Enlightenment-era secret society founded on 1 May 1776 in Bavaria, today part of Germany. The society's stated goals were to oppose superstition, obscurantism, religious influence over public life, and abuses of state power. "The order of the day," they wrote in their general statutes, "is to put an end to the machinations of the purveyors of injustice, to control them without dominating them." The Illuminati—along with Freemasonry and other secret societies—were outlawed through edict by Charles Theodore, Elector of Bavaria, with the encouragement of the Catholic Church, in 1784, 1785, 1787 and 1790. During subsequent years, the group was generally vilified by conservative and religious critics who claimed that the Illuminati continued underground and were responsible for the French Revolution.

A secret society is an organization about which the activities, events, inner functioning, or membership are concealed. The society may or may not attempt to conceal its existence. The term usually excludes covert groups, such as intelligence agencies or guerrilla warfare insurgencies, that hide their activities and memberships but maintain a public presence.