The fans at Comic-Con -- the world's largest comic book and popular culture convention -- will also see Iron Man director Jon Favreau premiere his new film, Cowboys & Aliens, starring Daniel Craig and Harrison Ford, while Sony will provide a sneak peek at The Amazing Spider-Man.
Many fans proudly dress up as their favourite comic book superhero, Star Wars character or anime creature.
For four days the 130,000 geeks, often ridiculed in the outside world for their passion for lycra-clad superheroes, can walk among friends, posing for photos with others in their elaborate costumes.
"Geeks rule at Comic-Con," Tony Vellas, a 28-year-old accountant from the west Sydney suburb of Lidcombe, proudly told AAP.
"It's the one time where we are the majority."
Mr Vellas was standing in a 400m long line that snaked its way around the San Diego Convention Center.
He was happily chatting away with fellow geeks also waiting to pick up their Comic-Con badges.
"I'll be in my Boba Fett outfit tomorrow," Mr Vellas, dressed in jeans and a t-shirt, said, referring to the Star Wars bounty hunter.
Comic-Con has grown from a small convention held in the basement of a rundown San Diego hotel four decades ago to one of the most influential dates for Hollywood's studios.
Each year studios attempt to whip the geeks into a frenzy with their new film offerings, rolling out big stars and screenings clips months before the movies appear in theatres.
Summit Entertainment brought the stars of The Twilight Saga: Breaking Dawn - Part 1, Kristen Stewart, Robert Pattinson, Taylor Lautner and director Bill Condon on stage in the convention centre's cavernous Hall H.
Twilight fans began camping outside Hall H 24 hours before the presentation to ensure a chance to see Stewart & Co.
TV networks, video game makers, memorabilia sellers and comic book retailers also stake out space in the convention centre.
"It's important to come to Comic-Con and show respect to the fans and talk to the media and bloggers and, hopefully, generate some buzz on the internet," David R. Ellis, director of the new horror film, Shark Night 3D, said.
Ellis is a Comic-Con veteran, bringing past films including 2004's Cellular, 2006's Snakes on a Plane and 2009's The Final Destination to San Diego before they screened in theatres.
"Cellular starred a guy named Chris Evans. He was an unknown back then," Ellis said of the Boston-born actor.
"Now look at Chris. He's the new Captain America."
