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(USA TODAY) "I'm always ready for Comic-Con!"

That could be any number of fanboys heading to San Diego this week for the annual pop-culture extravaganza. It just so happens that this particular fanboy is Vin Diesel, a longtimeDungeons & Dragonsgeek who also happens to be the face of the uber-popularFast & Furiousmovie franchise.

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No one's going to give him a wedgie, however.

More than 125,000 pop-culture devotees are expected to invade the San Diego Convention Center - many costumed and transformed into their favorite characters - to let their nerd flags fly for the hottest upcoming movies, TV shows, comic books and much more. The event, whose origins date to 1970, runs Thursday to Sunday.

Comic-Con's popularity still takes some by surprise, including Aaron Eckhart. "I went there forBattle: Los Angeles(in 2010), and I didn't have any idea that people were so fervently into their films, and there were whole families in costumes," says the actor, who this year will present footage from hisI, Frankenstein(out Jan. 24).

But geeking out with like-minded folks is the best part for Diesel, who's there for the first time in more than a decade with his filmRiddick(Sept. 6). "You are connecting with true fanboys, and you are speaking to that core audience."

Comic-Con's growing prominence allows it to attract huge celebrities - and we don't just mean Godzilla, though the monster will be there with a new movie, too. A-listers Hugh Jackman ofThe Wolverine(July 26) and Sandra Bullock of the sci-fi dramaGravity(Oct. 4) will be on hand for their movies. Sullivan Stapleton, Eva Green and Rodrigo Santoro will tout300: Rise of an Empire(due in March). Joss Whedon, the unofficial king of Comic-Con, brings the new showMarvel's Agents of S.H.I.E.L.D., which takes the world of superhero films to HD TV this fall. AndThe X-Filesstars David Duchovny and Gillian Anderson are back together for a special 20th-anniversary reunion panel.

Even the heavy-metal rock gods of Metallica will be there to promote their movieMetallica Through the Never(Sept. 27) and play a secret show. Maybe that's the real revenge of the nerds - if Metallica shows up at your party, you're really cool.

The best part for many is the surprise appearances. Marvel Studios is famous for pulling superhero rabbits out of its hat. At the 2010 gathering, the entire cast ofThe Avengersassembled on a stage for the first time. With a panel forThe Hunger Games: Catching Fire(Nov. 22) on tap, one could fathom a visit from newly minted Oscar winner Jennifer Lawrence, or perhaps Bullock'sGravity co-star George Clooney. Like many attendees, he put on a Batman costume once.

Some, such as British director Edgar Wright - who's doing a panel for his comedyThe World's End(Aug. 23) and hosting a fan screening in town - go all out because Comic-Con simply means a lot to them, too.

"It's why studios go there with films," Wright says."It's actually a way for filmmakers to intersect with fans that you can't in other situations."

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