"Spider-Man 3" isn't due until next summer, but about 5,000 fans got an early look at the film Saturday at Comic-Con, the country's largest comic book convention.

Director Sam Raimi, producer Laura Ziskin and key members of the cast — Tobey Maguire, Kirsten Dunst, Topher Grace, Bryce Dallas Howard and Thomas Haden Church — came to the San Diego Convention Center to answer fan questions and unveil never-before-seen, unfinished footage of the much-anticipated movie.

So is this the final installment of the franchise?

"There will be some conclusions, though I wouldn't say it's necessarily the end," said Maguire, whose words were nearly drowned out by thunderous applause. "We're going to leave it open-ended. If there are stories worth telling, then we'll tell them."

The brief teaser footage blended live-action scenes with animation and computer graphics. It showed Sandman, a new villain played by Church, and offered a quick glimpse of Venom (Grace), Peter Parker's spider-like nemesis.

"He's more of a doppelganger to Peter," Grace told the crowd. "It's kind of a case study in if someone very similar to Peter got the same powers but didn't have a good upbringing."

Raimi also revealed that Harry Osborn (James Franco) would become a third villain, taking on some of the powers of his father, the Green Goblin (Willem Dafoe), who was killed in the first "Spider-Man" film.

Actor Bruce Campbell, a Raimi-film regular, also makes an appearance in "Spider-Man 3," the director said. He'll play a new character, who fans believe will be the villain Mysterio.

As the director of all three "Spider-Man" films, Raimi has been immersed in Spidey's world for more than six years. A longtime fan of the comic books, Raimi said it's been a "super-dream" to make the movies, but also a "great responsibility to tell the story of this character that kids look up to as this great hero."

"Certainly you don't want to make anything that isn't worthy of their admiration," he said.

Based on early reaction at Comic-Con, Raimi has nothing to worry about. He delivered what fans wanted: Venom.

"It was way better than I expected because you got to see Venom. He looked awesome," said John McCracken, 22.

"He made the entire world happy by putting Venom in it," said Nora McGuirk, 26, manager of Beach Ball Comics in Anaheim, Calif. "Sam Raimi hasn't disappointed us yet."

Chastity Vicencio, 20, said it was even more exciting to see Spider-Man face his own demons.

"Superheroes are cool and all, but when they hit a dark side, that's really great," she said.

Spider-Man creator Stan Lee has his own ideas of what makes the movie a winner.

"I have a cameo in it, and I think it's my best cameo," said the 83-year-old Marvel Comics master. "That's probably the high point of the movie. After that, you know, it's all a letdown."