Shea met Wilson in the late 1960s when they worked on Playboy magazine. They decided to collaborate on a novel. It would combine sex, drugs, religious cults and conspiracies, as well as anarchy. Their philosophical and political differences merely served to enrich their efforts. Objectivity was jettisoned, as indeed was subjectivity: no single point of view or version of reality was privileged: Illuminatus! was the three-volume consequence.

Illuminati, a card game from Steve Jackson Games, was inspired by the books. A trading card game, New World Order, and a role-playing game, GURPS Illuminati, followed.

Shea provided in 1983 a brief introduction for the Illuminati Expansion Set rule book. "Maybe," he wrote, "the Illuminati are behind this game. They must be. They are, by definition, behind everything."

He and Wilson, though living in Chicago and California respectively, remained good friends in later years.

Shea went on to write historical action novels, including Shike (1981), All Things Are Lights (1986), and The Saracen, a novel published in two volumes in 1989 depicting the struggle between a blond Muslim warrior called Daoud ibn Abdullah and his French crusader adversary Simon de Gobignon. His last published book was the Native American tale Shaman (1991). These stories were straightforward beginning-middle-end tales, but included a few sly hints about the subjects of Illuminatus!

All Things Are Lights and the outline for the unfinished novel Children of Earthmaker have been released under a Creative Commons license and are available to read and copy at Robert Shea's website. Lady Yang was finished but never published; a Creative Commons online version is in the works by Shea's son Michael.

Three of his lectures and two panel discussions he participated in were recorded when he was a featured speaker at both the Starwood Festival and the WinterStar Symposium (both with and without Robert Anton Wilson) and produced by the Association for Consciousness Exploration.

For several years, Shea edited the anarchist zine No Governor. The title comes from a quote attributed to Zhuangzi, "There is no governor anywhere." The zine was mentioned in and read by one of the characters in Illuminatus!.

Clipped from the Robert J. Shea Tribute page:

Robert Joseph Shea attended Manhattan Prep, Manhattan College and Rutgers University and worked as a magazine editor in New York and Los Angeles. In the 60's he edited the Playboy Forum where he met Robert Anton Wilson, with whom he collaborated on Illuminatus! After publishing Illuminatus!, Bob left Playboy to become a full time novelist. His novels include: Shike, set in medieval Japan; All Things Are Lights, a story that entwines the fate of Cathars of southern France with the occult traditions of Courtly Love and the troubadours; The Saracen, describing the intricate politics of medieval Italy through the eyes of an Islamic warrior; Shaman, tracing the fate of the survivors of the Black Hawk War in 19th century Illinois; Lady Yang, a tragic story of an idealistic empress of medieval China.

Robert Shea is survived by his son, Michael E. Shea, and his second wife, author Patricia Monaghan.

• The Illuminatus! Trilogy (with Robert Anton Wilson) Full Trilogy printed December 1, 1983 by Dell: ISBN 0440539811, ISBN 978-0440539810
• The Eye in the Pyramid (1975) Dell
• The Golden Apple (1975) Dell
• Leviathan (1975) ISBN Dell

• Shike (January 13, 1992) Two in One version: Ballantine Books ISBN 034536046X, ISBN 978-0345360465
• Time of the Dragons (June 1, 1981) Jove ISBN 0515048747, ISBN 9780515048742
• Last of the Zinja (July 1, 1981) Jove ISBN 0515059447, ISBN 978-0515059441

• All Things Are Lights (April 12, 1986) Ballantine Books ISBN 0345329031, ISBN 978-0345329035 [1]

• From No Man's Land to Plaza del Lago (October 1987) Amer References ISBN 0913765082, ISBN 978-0913765081

• The Saracen
• Land of the Infidel (February 13, 1989) Ballantine Books ISBN 0345335880, ISBN 978-0345335883
• The Holy War (March 13, 1989) Ballantine Books ISBN 034535933X, ISBN 978-0345359339

• Shaman (February 20, 1991) Ballantine Books ISBN 0345360486, ISBN 978-0345360489

• Lady Yang - Unpublished Novel

• Children of Earthmaker Unfinished Novel