Chris Evans, Mark Ruffalo, Chris Hemsworth, Jeremy Renner and Robert Downey Jr were on hand with other cast members from The Avengers: Age of Ultron, including Samuel L Jackson and Cobie Smulders.
“It just keeps getting better,” Downey told the boisterous crowd of 6,500 assembled in the San Diego Convention Centre.
The footage kicked off with the Marvel superhero team comically attempting to pick up Thor’s mighty hammer from a coffee table.
“If I lift it, do I get to rule Asgard?” Tony Stark wondered while trying to wield the hammer.
The teaser quickly launched into a barrage of action-packed imagery, including Hulk battling a giant robot resembling Iron Man and Thor grabbing Stark by the throat.
The footage ended with a bleak scene of all the Avengers fallen with a haunting close-up of Captain America’s shield split down the middle.
Avengers director Joss Whedon was not present at the unveiling because he recently underwent knee surgery, nor was pregnant Black Widow actress Scarlett Johansson, who sent along a video message.
The original Avengers cast was joined on stage inside Hall H by newcomers Elizabeth Olsen, Aaron Taylor-Johnson, Paul Bettany and James Spader, who personifies the villainous mechanical force Ultron in the sequel.
“I play an eight-foot robot in this movie,” Spader joked. “I’ve always played humans up until this point.”