Cast
Edward Norton as Bruce Banner:A nuclear physicist and biochemist at Culver University who, because of exposure to gamma radiation, transforms into an enormous green humanoid monster when enraged or agitated. David Duchovny was a front-runner for the film before Norton's casting, while director Louis Leterrier's original choice was Mark Ruffalo, who would later play Banner in future Marvel Cinematic Universe (MCU) films. Producer Gale Anne Hurd recalled the duality of Norton's performances in the films Primal Fear (1996) and Fight Club (1999), while Norton reminded producer Kevin Feige of Bill Bixby, who played Banner in the 1978–1982 television series. Lou Ferrigno, who played the Hulk in that series, said Norton "has a similar physique [and a] similar personality" to Bixby. Norton was a Hulk fan, citing the early comic books, the Bixby series, and Bruce Jones's run on the comics as his favorite depictions of the character. He had expressed interest in the role for the previous film, Hulk (2003), and was initially reluctant to take on the part after that film had strayed from the fugitive story that he associated with the character. He was won over by the vision of Leterrier and Marvel Studios and believed they were looking to him to guide the project. Norton subsequently rewrote the script. Leterrier praised Norton for bringing gravitas to the script, and said they were both approaching superheroes as "the new Greek gods". Norton was particularly drawn to the Greek myth of Prometheus for the character.
Lou Ferrigno voices the Hulk. During the 2008 New York Comic Con, Leterrier publicly offered Ferrigno the role. This marks the third time Ferrigno portrayed the Hulk, having also voiced the character in the 1996–97 animated series. Originally, the Hulk's only line was "Betty" at the film's ending, which would have been his first word. Leterrier was aware that fans wanted him to speak normally and added "Leave me alone!" and "Hulk smash!". The latter line received cheers during a screening Leterrier attended. Ferrigno also has a cameo appearance in the film as a security guard whom Banner bribes with a pizza.
Liv Tyler as Betty Ross:A cellular biologist and Bruce's former girlfriend, from whom he is separated as a result of his condition. Tyler was attracted to the love story in the script and was a fan of the Bixby series because of the "humanity and what [Banner] is going through". She was called about the role while driving home and 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 physical and 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 in the United Kingdom's Royal Marines Commandos who is loaned to General Ross. Lusting for the Hulk's power, Blonsky is injected with various serums that transform him into a near-skeletal humanoid monster as strong as the Hulk himself. Roth said he took the part to please his sons, who are comic-book superhero fans, and because he found Leterrier's ideas "very dark and very interesting". Roth was a fan of the Bixby series as a teenager. He started watching the 2003 film to prepare for the part, but stopped as he did not want to compare himself to it. It was Roth who suggested Blonsky be a soldier rather than a KGB agent as in the comics. Leterrier was a fan of Roth's work and felt it was "great watching a normal Cockney boy become a superhero", but Marvel and Norton were initially reluctant to cast him. Before he was cast in the film Punisher: War Zone (2008), Ray Stevenson was in discussions for the role. Roth trained with gun and military experts in preparation for the role, but it did not work out due to Blonsky's aging. This made it difficult to film some stunts, including being pulled by a harness to show Blonsky's enhanced 30–40 mile-per-hour running speed. Cyril Raffaelli performed some of his stunts. Roth enjoyed the motion capture for Abomination, which reminded him of fringe theatre. He worked with Terry Notary, his trainer from the film Planet of the Apes (2001), on the monster's movement. Roth was signed on for three more films.
William Hurt as Thaddeus Ross:Betty's father and a U.S. Army general who has dedicated his life to capturing the Hulk. Leterrier cast Hurt because "Ross is more physical, more explosive in this movie, and no actor goes from zero to 100 as well as William". He compared Ross to Captain Ahab. The Hulk was Hurt's favorite superhero, and his son is also a big fan of the character. Hurt found production very different from the typical "pure anxiety" of a studio film, finding it more akin to an independent film. He described Ross as "humiliated by Hulk's conscience: he actually sees and recognizes that it's more developed than his own, even though he's a patriot and a warrior for his country. He's sacrificed [much] for that purpose, but at the expense at times of his humanity—which he occasionally recovers." In June 2015, when reflecting on how his reprisal in the MCU film Captain America: Civil War (2016) was different from this film, Hurt said, "What I created [for The Incredible Hulk] was a Ross who was right out of the graphic novel type of thing, where he was as much of a cartoon, in a way, as the monsters were. His ego was just as big and his problems were just as big. I really did do that consciously. I created a General Ross before which created a verisimilitude for the monsters, by making him a human monster. I worked really hard on the makeup and the exaggerated behavior and things like that and a controlled psychosis." Sam Elliott had expressed interest in reprising the role from the 2003 film before Hurt was cast.
Tim Blake Nelson as Samuel Sterns:A cellular biologist who develops a possible antidote to Banner's condition. Towards the end of the film, Sterns is exposed to a substance that begins his transformation into the comic book villain "The Leader".
Ty Burrell as Leonard Samson:A psychiatrist who is in a relationship with Betty during Bruce's absence. Burrell had performed with Norton in the off Broadway play Burn This in 2003, and when Leterrier met him, he recognized Burrell as the "jerk" from the 2004 Dawn of the Dead remake, which was how Samson was characterized in the script before Norton rewrote it.
Christina Cabot as Kathleen Sparr: A U.S. Army major who is General Ross's personal aide
Robert Downey Jr. makes an uncredited cameo appearance as Tony Stark at the end of the film, reprising his role from the MCU film Iron Man (2008). Downey appeared as a favor to Marvel Studios and was frustrated about being constantly asked about his short cameo while promoting Iron Man. He acknowledged that this was a smart move on Marvel's part, bringing more attention to The Incredible Hulk. Hulk co-creator Stan Lee cameos as a man who becomes ill when drinking soda that is poisoned with Banner's blood. Paul Soles, who voiced Banner in the 1966 The Marvel Super Heroes animated series, appears as kindly pizzeria owner Stanley Lieber, who was friends with Banner and Betty in the past. His name is a reference to Stan Lee's full name. P. J. Kerr and Nicholas Rose portray respective Culver University students Jim Wilson and Jack McGee. Other small roles include: Brazilian Jiu-Jitsu artist Rickson Gracie as Bruce Banner's martial arts instructor, credited as an Aikido instructor due to Norton's background with that style; Brazilian actress Débora Nascimento as Martina, Banner's colleague at a beverage factory; Michael K. Williams as a Harlem bystander, a role that was written for him by Norton as a fan of Williams's series The Wire (2002–2008); and Peter Mensah as General Joe Greller, one of Ross's military friends. Additionally, Martin Starr plays a college student who is credited as "Computer Nerd". In May 2019, Feige said this character had been retroactively named Roger Harrington, which is Starr's role in the MCU films Spider-Man: Homecoming (2017), Spider-Man: Far From Home (2019), and Spider-Man: No Way Home (2021).