Part of that will address some characters and plot points first brought to light in 2008's The Incredible Hulk, which was only the MCU's second movie. She-Hulk: Attorney at Law started to revisit that history more deeply upon its Disney+ debut, although the next Captain America 4 will take that idea to a new level.
With that being said, here are three characters from The Incredible Hulk that are set to have a major impact on the events of Captain America 4.
Hulk Characters Returning in Captain America: New World Order
1.) Thaddeus "Thunderbolt" Ross
Returning as an important supporting player in Captain America 4 will be General Thunderbolt Ross, making his sixth appearance in the MCU since 2008's The Incredible Hulk. This time, after the passing of original General Ross star William Hurt, the role will be played by Star Wars icon Harrison Ford.
In Ross' first Phase 5 appearance, he'll reportedly take on a new role in the story as he moves from his post as Secretary of State to serve as the President of the United States. And while Ford has been diligent in not revealing anything about how he fits into the story, he's expected to play an important part in how Captain America's story moves forward.
He'll also be part of what ties this sequel to the events of Captain America: Civil War, with Sam's imprisonment in the Raft still being a sore spot between him and Ross.
And with Ross having an impact on the MCU throughout Phase 3 and Phase 4, with rumors of him potentially evolving further into Red Hulk on the table, his presence won't have a light impact on Cap's next adventure.
2.) Betty Ross
For the first time in 15 years, Liv Tyler will be back in the MCU as Elizabeth "Betty" Ross, marking only her second appearance in the MCU. Initially serving as a love interest for Edward Norton's Bruce Banner in The Incredible Hulk, the only sign of Betty's existence since then has come in the animated What If...? series on Disney+, with no mention of her in any form otherwise.
When filming for Captain America 4 first kicked off in March 2023, Tyler was seen in her comeback for the first time in a black formal outfit as she attended a funeral, although there are no signs pointing to who the funeral is honoring.
This return will also give Betty a chance to reunite with her father and rekindle their already tumultuous relationship, although there's no telling how either of them will approach that family reunion after so much time apart.
3.) Samuel Sterns/The Leader
Also making a long-awaited comeback to the MCU is Tim Blake Nelson, who will reprise his role as Dr. Samuel Sterns alongside Ford and Tyler. As was the case with Tyler, this will be only his second time playing Sterns in the MCU, although Captain America 4 finally allows him to evolve into his comic-accurate alter-ego - the Leader.
Before the final battle in The Incredible Hulk, Sterns was infected with Bruce Banner's blood, having it drip into an open wound in his head after the Abomination fully powered up. While this turned into one of the MCU's longest-standing unresolved plot threads due to Nelson's 15-year absence, he's finally about to rise to power in his first movie as a villain.
Rumors have also pointed to the Serpent Society being involved in Captain America 4, with Valentina Allegra di Fontaine searching for what could be the MCU's take on Adamantium.
How the Leader mixes with that plot point is still a mystery, as are his potential motivations, although he'll be out to stake his claim on the world with Captain America directly in his path.
Will Other Hulk Characters Show Up in Captain America 4?
Captain America 4 will be the deepest exploration of plot threads laid out in The Incredible Hulk on the big screen since Bruce Banner's first solo movie debuted. And with that trio of big names playing such big roles in Sam Wilson's first solo movie, it does beg the question - will there be more heroes from the Hulk's legacy to join the fray?
Rumors already pointed to a potential appearance for Tatiana Maslany's Jennifer Walters, with other reports revealing that the Leader was almost included in her own solo series. This would give her a first interaction with Avengers with which she doesn't share a blood relation, which would be especially exciting considering she's likely to play a big role in future movies for Earth's Mightiest Heroes.
And with She-Hulk possibly involved, theories then turn to Bruce Banner, one of the few original Avengers left on the playing field.
Wilson and Banner don't have an extensive relationship with one another on screen after the Infinity Saga, as the two simply don't appear in too many scenes where they interact with one another. But with Steve Rogers' ties to Bruce from past projects (not to mention the reveal centered on Rogers' virginity from Episode 1 of She-Hulk), it wouldn't be a surprise to see Banner foster closer ties with the new Cap.
No matter how the Hulk's legacy is brought into Captain America 4, this movie will finally give that story the chance to shine after legalities kept the angry green Avenger limited to MCU team-up movies.
And with filming now moving forward for Sam Wilson's first MCU solo movie, more of these ties could make their way into the light as the year moves forward.
Captain America: New World Order will debut in theaters on May 3, 2024.