Edward Norton as Bruce Banner / Hulk
A genius scientist who, because of exposure to gamma radiation, transforms into the Hulk when stressed, enraged, or excited.
David Duchovny was a front-runner for the film before Norton's casting, while Louis Leterrier originally wanted Mark Ruffalo (who would later play Banner in Marvel's The Avengers) for the role.
Gale Anne Hurd recalled Norton's portrayals of duality in Primal Fear and Fight Club, while Norton reminded Kevin Feige of Bill Bixby, who played Banner in the TV series.
Lou Ferrigno, who played the Hulk with Bixby, remarked Norton "has a similar physique and a similar personality".
Norton was a Hulk fan, citing the first comic appearances, the Bixby TV show, and Bruce Jones' run on the comic, as his favorite depictions of the character.
He had expressed interest in the role for the first film. He initially turned down the part for this film, recalling "there was the wince factor or the defensive part of you that recoils at what the bad version of what that would be."
He felt the previous film "strayed far afield from a story that was familiar to people, which is a fugitive story".
When he met Leterrier and Marvel, he liked their vision, and believed they were looking to him to guide the project. Thus, Norton rewrote the script.
"Edward's script has given Bruce's story real gravitas," Leterrier said. "Admittedly I'm not the most adult director, but just because we're making a superhero movie it doesn't have to just appeal to 13-year-old boys. Ed and I both see superheroes as the new Greek gods."
Liv Tyler as Betty Ross
Bruce's girlfriend, whom he is separated from due to his condition, and a cellular biologist. Tyler replaced actress Jennifer Connelly, who portrayed Betty Ross in the 2003 film Hulk.
Tyler and Connelly had previously played sisters in the 1997 film Inventing the Abbotts. Tyler was attracted to the love story in the script, and was a fan of the TV show, because of the "humanity and what Banner is going through".
She was called about the role while driving to her home, and she accepted the part after a day without reading the script. Tyler and Norton spent hours discussing Bruce and Betty's life before he became the Hulk.
She said filming the part "was very physical, which was fun", and compared her performance to "a deer caught in the headlights", because of Betty's shock at Bruce's unexpected return into her life.
Tim Roth as Emil Blonsky / Abomination
A Russian-born officer from the United Kingdom's Royal Marines Commandos loaned to General Ross and becomes the monster called Abomination.
Recognizing he is past his prime, he lusts after the Hulk's power. Roth said he took the part to please his sons, who are comic-book superhero fans.
As a teenager, Roth was a fan of the 1970s TV series, and he also found Leterrier's ideas "very dark and very interesting".
Roth started watching the 2003 film to prepare for the part, but stopped as he did not want to be caught up in the controversy over its quality, and to compare himself to it.
It was Roth who suggested Blonsky be a soldier, whereas in the comics he was a KGB agent.
Leterrier is a fan of Roth's work, and felt "it's great watching a normal Cockney boy become a superhero!", but Marvel and Norton were initially reluctant to cast him.
Before he was cast in Punisher: War Zone, Ray Stevenson was in discussions for the role. Roth prepared for the part by learning to fire guns and break into rooms with two experts.
Roth found it tough shooting the chases, because he could not work out to show Blonsky's aging. He especially found it difficult to run while pulled with a harness, which was used to show the injected Blonsky's 30–40-mile per hour running abilities.
Cyril Raffaelli performed some of Roth's stunts. Roth enjoyed the motion capture, which reminded him of fringe theatre, and he hired his trainer from Planet of the Apes to aid him in portraying the monster's movement.