Some 130,000 devotees of comic books, movies and TV shows -- many dressed up in the costumes of their idols -- will throng into the sold-out Convention Center and myriad events around the southern Californian city through Sunday.
Other big draws at the 43rd annual Comic-Con International include Hollywood veterans like Arnold Schwarzenegger -- returning from politics in "The Expendables 2" -- Robert Downey Jr ("Iron Man 3"), Jodie Foster and Matt Damon.
"Twilight" fans will be looking out for Robert Pattinson and Kristen Stewart, in town to promote the final installment of the fantasy films, "The Twilight Saga: Breaking Dawn, Part 2," due out in November.
In a sign of the frenzy generated by the movie, they have been lining up since last weekend for the "Twilight" panel on Thursday. One fan died when crossing the street nearby Tuesday, triggering a tide of grief on Twitter.
The other big movie event of Comic-Con 2012 will be the screening of more footage from Peter Jackson's "Lord of the Rings" prequel "The Hobbit: An Unexpected Journey," due for release in December.
Anticipation if particularly intense because a first glimpse of the movie, shot in groundbreaking 48 frames per second format, drew mixed critical reactions when it was screened in Las Vegas in April.
In an interview with the the LA Times published Wednesday, director Jackson said he would screen the footage at Comic-Con in the normal 24 frames per second.
"With our 48 frames per second presentation, negative bloggers are the ones the mainstream press runs with and quotes from," he said.
"I decided to screen the 'Hobbit' reel at Comic-Con in 2-D and 24 frames per second, so the focus stays firmly with the content and not the technical stuff. If people want 3-D and 48fps, that choice will be there for them in December."
Hollywood, two hours up the California coast from San Diego, has not always played such a big role at Comic-Con.
"Hollywood wasn't involved in the beginning as it is today," David Glanzer, Comic-Con's marketing chief. "But .. Hollywood is a great partner and we hope they enjoy Comic-Con as much as we enjoy their participation," he added.
Television bosses will also be showcasing their wares in San Diego: small screen highlights include HBO fantasy hit "Game of Thrones," a new season of "Glee," and Britain's "Dr. Who," seeking to build on its US fan base.
Video games have also played a growing part at Comic-Con. Those presenting new material this year include "Assassin's Creed III," "Halo 4" and "Resident Evil."
Many Comic-Con attendees openly embrace the description of them as geeks, or nerds, and there will be a predominance of young men dressed up as superheros, or Middle Earth thronging the San Diego streets over the next few days.
But a growing number of women are also joining the party.
"The key demographics remain male 16 to 34. However, we have seen a marked increase in female attendance over the years. Currently the male to female ratio is about 60/40," said Glanzer.
And he declined to predict what will emerge as the overall highlight of the festival.
"When asked what the big thing will be at Comic-Con this year, I always say we have to wait until the end of the show. There are always predictions, but it's the fans who will let us know when all is said and done," he said. AFP
