Captain America: New World Order director Julius Onah has cited an exciting reason for why he signed on to the upcoming Marvel sequel: Tim Blake Nelson's return as The Leader.

It was revealed during this year's D23 Expo that Nelson will reprise his role from 2008's The Incredible Hulk role as Samuel Sterns, now in his green-skinned, bulb-headed form as The Leader, in New World Order. Onah talked enthusiastically about the villain's role in the fourth Captain America film during an interview with ComicBook.com's Phase Zero following the announcement. "One of the things that really drew me to this project is the Leader is a man who operates from intellect," he said. "And it's so great to have an adversary who is working with this incredible intellect to really put Sam [Wilson] through the wringer in this story."

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Onah talked further about Captain America 4, which he described as being "a paranoid thriller" film. "It's this grounded adventure where I think everything that happens in this film feels so real and intense because of who this adversary is," he explained. "What [Captain America is] going to have to go through in this film is because he's got an adversary who is so terrifyingly intelligent."

Created by Stan Lee and Steve Ditko, The Leader has been a longtime enemy of The Hulk over the course of his comic book history. First appearing in 1964's Tales to Astonish #62, the character, Samuel Sterns, was exposed to gamma radiation similar to what turned Bruce Banner into the Hulk, only he was granted superhuman intellect instead of strength. Likewise, The Incredible Hulk depicted Nelson's version of Sterns as a scientist who was attempting to cure Bruce Banner (Edward Norton) of his Hulk problem, resulting in another gamma-related disaster. Thus, his final scene in the film showed his brain beginning to mutate after it became exposed to Banner's blood, hinting at a future as The Leader. However, Nelson's character failed to reappear in the Marvel Cinematic Universe, meaning that New World Order will pay off a tease set up nearly two decades prior.

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It's been a whirlwind ride for Onah since the July announcement that revealed he's directing New World Order. The Steve-Rogers-deprived Captain America fourquel will center on Sam Wilson (Anthony Mackie) following his decision to assume the titular mantle in the 2021 Disney+ TV series The Falcon and the Winter Soldier. While the director's interest in the film was over a minor character from The Incredible Hulk, the film's main villain was coincidentally responsible for the director getting the job. Indeed, Tim Roth, who appeared as Emil Blonsky/Abomination in the 2008 film, recently revealed that Marvel Studios asked him about his experience with Onah on the set of 2019's Luce prior to hiring the filmmaker, thus providing a crucial work reference.

Captain America: New World Order will hit theaters on May 3, 2024.

Source: ComicBook's Phase Zero via Murphy's Multiverse