Magnum Opus Con (MOC) was an annual multigenre convention which generally took place each spring in various cities in the U.S. states of Georgia and South Carolina from 1986 to 2001.

Along with panels, seminars, and workshops with industry professionals, MOC often featured previews of upcoming films and even a celebrity softball game.

Magnum Opus Con worked on a "membership" basis, which enabled attendees to gain admittance to the convention for the entire weekend.

[5] Castle created a nonprofit, the Middle Georgia Society for Fantasy and Science Fiction, under which to run the show, and the first MOC was held April 18–20, 1986, at the Macon Hilton.

For MOC 4, held March 17–19, 1989, the convention shifted locations 250 miles to Greenville, South Carolina, and the Hyatt Regency, where it stayed for six years.

After five years in Greenville, South Carolina, Castle moved MOC 225 miles to Callaway Gardens, in Pine Mountain, Georgia.

[citation needed] MOC 11 was held June 13–16, 1996, at the Downtown Radisson, in Atlanta, Georgia, again in competition with Dragon Con (which took place the following weekend).

MOC 12 returned to its traditional March schedule, staying in Atlanta, and featuring comics guests like Keith Giffen, Alan Grant, and Simon Bisley.

MOC 15, held March 31–April 2, 2000, was Roland Castle's final show as convention chairman; he stepped down early the next year[12] due to stress-related health reasons.

[9] Robinson and Bell dubbed MOC 16 " The Sweet Sixteen Party,"[12] which was held March 15–18, 2001, at the Ramada Plaza Hotel Perimeter North, in Atlanta.

Over the years, MOC guests included Doctor Who actors like Colin Baker, Tom Baker, Louise Jameson, Jon Pertwee, and Patrick Troughton; Star Trek actors James Doohan, DeForest Kelley, George Takei and Grace Lee Whitney, celebrities like Bruce Boxleitner, Bruce Campbell, Phyllis Coates, Yvonne Craig, Chris Potter, and Tom Savini, science fiction authors Robert Asprin, Ben Bova, Marion Zimmer Bradley, Lois McMaster Bujold, Brad Strickland, David Weber, Timothy Zahn, and Roger Zelazny; comics creators like Keith Giffen, Alan Grant, Simon Bisley, Garth Ennis, John McCrea; and former astronauts Bruce McCandless II, Story Musgrave, and Robert C. Springer.

The 'zine highlighted guests and events, showcased cosplay cheesecake photos, and served as a forum for Castle and MOC attendees to communicate.