Particularly since the 1960s, conspiracy theory has been a popular subject of fiction. A common theme in such works is that characters discovering a secretive conspiracy may be unable to tell what is true about the conspiracy, or even what is real: rumors, lies, propaganda, and counter-propaganda build upon one another until what is conspiracy and what is coincidence becomes an unmanageable question.

'High' literature

Umberto Eco's Foucault's Pendulum, features a story in which the staff of a publishing firm, intending to create a series of popular occult books, invent their own occult conspiracy, over which they lose control as it begins to be believed.

Thomas Pynchon's The Crying of Lot 49, includes a secretive conflict between cartels dating back to the Middle Ages, such as the Phoebus cartel.

Popular novels

Illuminatus!, a trilogy by Robert Shea and Robert Anton Wilson, is regarded by many as the definitive work of 20th-century conspiracy fiction. Set in the late '60s, it is a psychedelic tale which fuses mystery, science fiction, horror, and comedy in its exhibition (and mourning, and mocking) of one of the more paranoid periods of recent history. The popular, humorous trading card game Illuminati New World Order is based in part on Shea and Wilson's fantasy.

The popular 2003 novel The Da Vinci Code draws on ideas of conspiracy involving the Catholic Church, including the real organization Opus Dei and the (probably fabricated) Priory of Sion.

Other authors who have dealt with conspiracy themes include Philip K. Dick and Robert Ludlum. Some might also categorize several of the Cthulhu Mythos stories of H. P. Lovecraft and others as conspiracy-related, though they might be more closely described as occult horror.

Television

The X-Files, a long-running 1990s TV drama series, continued a long tradition of B-movie-type plots and conspiracies, employing almost every available conspiracy theory in the course of its lifetime.

Cinema

Oliver Stone's Academy Award-winning 1991 film JFK — based on books by New Orleans District Attorney Jim Garrison and conspiracy author Jim Marrs — suggests that President John F. Kennedy was not killed by Lee Harvey Oswald acting alone, but rather by a group opposed to Kennedy's policies, especially his supposed reluctance to invade Cuba to overthrow Fidel Castro, and Kennedy's purported eagerness to withdraw American armed forces from the Vietnam War. Members of the CIA, the Military-Industrial Complex, and President Lyndon Baines Johnson are implicated as responsible for Kennedy's assassination. Stone has stated that JFK was intended as a Fable to counter the Warren Commission's conclusions, with which Stone disagreed. In fact, most of the claims in "JFK" have been disproven, most notably by the History Channel.

The 1997 movie Wag the Dog involves a pre-election attempt in the US by a spin doctor and a Hollywood producer who join forces to fabricate a war in a Balkan state in order to cover-up a presidential sex scandal. Interestingly, it was made before the Clinton / Lewinski scandal and the US led Kosovo intervention.

The Matrix, in which everyday reality is revealed to the protagonist to be a virtual reality environment created by robots, might be seen as a form of conspiracy tale.

Gaming narratives

The video games Metal Gear Solid and Metal Gear Solid 2 also contain a shadowy group known as "The Patriots" who manipulate politics in America. There are also references to numerous conspiracies in the game. The computer game Deus Ex is also filled with various references to conspiracies like the Illuminati, Majestic 12 and Knights Templar. The video game Broken Sword, based on Umberto Eco's book, also features the Knights Templar among other conspiracies. Act Of War features an industrial conspiracy plot to take control of oil reserves and the infrastructure of the US.

The role-playing game and card game GURPS Illuminati, by Steve Jackson Games (www.sjgames.com), feature conspiracy theories from the humorous side. The illuminated pyramid is notably the company's logo. Pagan Publishing's Delta Green and Delta Green Countdown books provide a more serious perspective on conspiracies in role-playing game, and relate them with the works of the late H. P. Lovecraft.