This weekend, upwards of 130,000 people will descend on San Diego for the annual rite known as Comic-Con. They will buy comic books, action figures and other pop culture tchotchkes. They will attend panel sessions on topics ranging from academic discussions of intellectual property and the theories of sequential art, to tutorials on how to create Star Wars origami figures. They will wait in long lines to enter the cavernous 6,500 seat Hall H to watch clips of forthcoming Hollywood features. They will line up to ask questions of celebrities such as actors Sylvester Stallone, Jessica Biel and Jodie Foster; comic book impresario Stan Lee; and writer/director Joss Whedon (and, yes, at Comic-Con, Lee and Whedon are very big stars). And many will do all of this wearing the costume of their favorite comic book character.

San Diego Comic-Con kicked off in 1970, when around 300 people assembled in the basement of the US Grant Hotel and, after short stints at other venues, moved in 1990 to the San Diego Convention Center, where it has remained – and has grown in both scale and scope – ever since.

The current Comic-Con is so large it no longer fits within San Diego’s Convention Center. Official sessions spill over into ballrooms in the neighboring Marriott and Hilton hotels. Additional related events are spread throughout San Diego – including Yahoo Movies’ life-sized board game, a “Dawn of the Con” welcome party hosted by rocker Rob Zombie, the traditional zombie walk through the streets of San Diego, and a new “Walking Dead” zombie escape at the San Diego Padres’ Petco park.

The Dawn of the Con

The origin of the comic-cons was even earlier than the San Diego event, reaching back to what is known as the “Silver Age” of comic books. In the early 1960s comic book fans like Jerry Bails and Roy Thomas created self-published “fanzines” whose readership began to establish a loose confederation of comic book aficionados. In 1964, around one or two hundred of these fans got together in New York to share their interest in comic books.

At a recent New York Comic-Con – now held annually at the spacious glass-and-steel Jacob K. Javits Center – Michael Uslan, executive producer of the Batman films anda  life-long comic book fan, described his experience attending that first gathering in New York as a young boy accompanied by his parents. That early conference was held in “a flea-bag hotel just off the Bowery,” Uslan recounted. “As we checked into the hotel we had to literally step over an unconscious drunk in the hallway and there were roaches on the walls. My mother was absolutely apoplectic. She said, ‘We’re outta here.’” Fortunately, Uslan’s father interceded and he was able to attend the conference.

New York currently hosts two different comic-cons: New York Comic-Con, produced by the ReedPOP division of publisher Reed Elsevier, which now attracts more than 100,000 attendees, and the older, but smaller, Big Apple Con run by Wizard Entertainment. Additional comic book, science fiction and fantasy conventions of varying size and scope are now held around the U.S. and in many other countries.

While the proliferation of comic-cons is a boon for fans who can’t travel – or can’t get a ticket – to the major events in San Diego and New York, it has also produced a great deal of confusion.

When people speak of “comic-con,” they typically mean the annual event in San Diego every July, officially known as “Comic-Con International: San Diego.” But the term “comic-con” – an abbreviation of “comic [book] convention” – is used to refer to dozens of events in the U.S. and elsewhere of varying scope, run by different organizations. To make matters even more confusing, Comic-Con International, the non-profit organization that runs the preeminent con in San Diego, hosts another significant, very similar, event in San Francisco which is called “WonderCon,” rather than the more logical “San Francisco Comic-Con” or “Comic-Con International: San Francisco.”

The Evolving Con

Although still called “comic-con,” the event has expanded beyond its comic book roots to embrace all things relating to science fiction, fantasy and popular culture. The San Diego convention – with its geographic proximity to Los Angeles – is heavily weighted toward the movie and television industry. The largest sessions feature Hollywood fare. The year’s Hall H events include screenings and q&a sessions with the cast and crew of “The Walking Dead,” “Game of Thrones,” Quentin Tarantino’s Django Unchained, the forthcoming Superman film Man of Steel, The Hobbit: An Unexpected Journey, Iron Man 3, The Expendables 2 – Real American Heroes, and The Twilight Saga: Breaking Dawn-Part 2 – just to name a few.

Many of the old-line comic-book faithful decry how movies and TV events have eclipsed the comic book roots of the cons. And the hard-core horror fans make snide comments about the Twilight crowd and their “sparkly vampires.”

But the Comic-Con has always been evolving. And science fiction and fantasy movies have been a part of it for many years. As Comic-Con International’s director of marketing and public relations David Glanzer noted to San Diego’s Daily Transcript a few years ago, Hollywood’s arrival on the Comic-Con scene is not a new phenomenon. Famed movie director Frank Capra was a guest at the San Diego event in the early 1970s. And George Lucas was there in 1976 to unveil his forthcoming science fiction film, Star Wars. By 2003, stars such as Angelina Jolie (promoting Lara Croft: Tomb Raider) and Halle Berry (supporting Gothika) were in attendance.

Comic-Con’s increasing emphasis on movies and television reflects the trend in the entertainment industry at large. While comic books no longer dominate popular culture as they did in the 1940s and early 1950s, they are a major influence on Hollywood. This summer’s first major blockbuster, The Avengers, is based on the Marvel superhero comic book. The Amazing Spider-Man grossed $140 million in U.S. box office receipts from July 3 through the subsequent weekend, bringing its global total to over $340 million. In a few more weeks, The Dark Knight Rises, the third in the series of Batman films directed by Christopher Nolan, is expected to challenge The Avengers in the summer box office bonanza.

Comic books may not be the nexus of youthful entertainment that they were in the pre-television era of the 1940s and early 50s, but their stories, characters and mythology continue to infuse much of popular culture.

The mythology of comic book superheroes has always been malleable – open to expansion and new interpretations. The Superman who appeared in the midst of the depression in 1938 was different from the Superman as portrayed in D.C. Comics’ recent “New 52″ revamp. The original Batman as realized by Bob Kane, Bill Finger and Jerry Robinson was a mysterious detective crime-fighter. The character was recast in the early 1960s as a more absurdist fantasy character. In the 1970s, Batman was redefined again by writer Denny O’Neil and artist Neal Adams and was envisioned anew in the 1980s as a psychologically disturbed “dark knight” by writers like Frank Miller, Alan Moore and Grant Morrison. With each new interpretation, the mythology of these characters becomes richer, deeper and more complex.

It seems only appropriate that the comic book convention should similarly evolve to encompass the full spectrum of media embracing super-heroes, science fiction and fantasy. From comic books to television, movies and video games, tales of great adventure will unfold this weekend at San Diego Comic-Con.

This blog post was written by Kendall Whitehouse, Wharton director of new media. For Whitehouse’s reports of past comic-cons, see his blog On Technology and Media.