Every Villain In Captain America 4 Explained

Marvel Studios has already confirmed that Sam Wilson, now Captain America in the MCU, will take on several different villains in 2025’s upcoming Captain America: Brave New World. Anthony Mackie’s Sam Wilson officially became Captain America at the end of 2021’s The Falcon and the Winter Soldier, but Brave New World will mark his theatrical debut as the Star-Spangled Man. Following in Steve Rogers’ footsteps is a tall order, so Marvel Studios’ Captain America: Brave New World needs to make a strong impression, and it’s doing this through its villains.

While most superheroes in the MCU take on perhaps one or two villains in their solo movies, Sam Wilson’s Captain America is set to take on a plethora of brilliant antagonists in his first headliner movie. Trailers for Captain America: Brave New World and set photos from the production of the Phase 5 movie have, so far, confirmed five powerful villains making their debuts or returns to the MCU. These villains will surely create a huge web of problems for Sam Wilson’s Captain America, but could set up some thrilling new stories for the MCU’s future.

5 Seth Voelker’s Sidewinder

Sidewinder Will Be Played By Giancarlo Esposito In Captain America: Brave New World

Giancarlo Esposito had been at the center of huge fan speculation for quite some time, with many fan-casting him in some iconic Marvel roles, including Professor X. Esposito confirmed his casting in the MCU during a panel at CCXP in Brazil in May 2024, and he announced this role to be Seth Voelker, a.k.a. Sidewinder, the King of the Serpent Society, during 2024’s SDCC. The Serpent Society is a formidable group of snake-themed villains in Marvel Comics, led by the teleporter Sidewinder, so will likely pose a huge threat to Sam Wilson’s Captain America.

The Serpent Society was originally teased as the villainous group of the third
Captain America
movie before Marvel boss Kevin Feige revealed that this project would actually be
Captain America: Civil War
.

Little has been revealed about Sidewinder and the Serpent Society’s role in Captain America: Brave New World, though trailers for the movie have shown Giancarlo Esposito’s villain walking around vehicles with an array of weapons, presumably in search of Sam Wilson. Sidewinder took on Steve Rogers’ Captain America several times in Marvel Comics, while Sam Wilson’s version of the patriotic hero fought new versions of the Serpent Society. There is also the chance that Sidewinder’s debut could lead to the introduction of more Serpent Society members.

While Giancarlo Esposito is expected to have a relatively small role in Captain America: Brave New World, the Better Call Saul, Kaleidoscope and The Boys star has teased future adventures for Seth Voelker in the MCU. In fact, Esposito has previously teased that Sidewinder will be appearing in a Disney+ series following his debut in Captain America: Brave New World, though whether this will be a series focused on him and the Serpent Society is yet to be confirmed. It will be interesting to see how the outlandish Sidewinder has been adapted for the live-action MCU.

4 Rachel Leighton’s Diamondback

Diamondback Will Be Played By Rosa Salazar In Captain America: Brave New World

Sidewinder’s debut creates the opportunity for other Serpent Society members to appear in Captain America: Brave New World, including Rachel Leighton’s Diamondback. Diamondback originally made her first Marvel Comics appearance as a supervillain in 1985, where she was introduced as one of the original members of the Serpent Society. While Diamondback hasn’t appeared in trailers, set photos from Captain America: Brave New World have shown off Rosa Salazar in a bright pink-haired role, which is instantly reminiscent of Diamondback, though this hasn’t actually been confirmed.

Eventually, Rachel Leighton decided to turn against her Serpent Society teammates when she began to express romantic feelings for Steve Rogers’ Captain America. She formed the heroic group BAD Girls, Inc. alongside Black Mamba and Asp, two former members of the Serpent Society, and also became an agent of SHIELD, though dipped her toe into her criminal roots on several occasions. Diamondback, not to be confused with the Luke Cage villain portrayed by Erik LaRay Harvey, could shake up Sam Wilson’s world in some major ways.

Since his debut in 2014’s Captain America: The Winter Soldier, the only piece of Sam Wilson’s personal life that has been explored has been his relationship with his sister, Sarah, in The Falcon and the Winter Soldier. Introducing Diamondback in Captain America: Brave New World could debut a complex love interest for Anthony Mackie’s Avenger, which could investigate new sides to the Captain America story that not even Steve Rogers did: falling in love with a villain. The Serpent Society’s debut will contribute to a darker tone in Captain America: Brave New World, which is very exciting.

3 Mind-Controlled Isaiah Bradley

Isaiah Bradley Will Be Played By Carl Lumbly In Captain America: Brave New World

Carl Lumbly first appeared as Isaiah Bradley in The Falcon and the Winter Soldier, and is set to return in Captain America: Brave New World, but with a twist. The Falcon and the Winter Soldier revealed Isaiah had become a super soldier in the 1950s to fight during the Korean War, but, fearing the ramifications of a Black super soldier, the government subsequently imprisoned him for the next 30 years. After becoming Captain America, Sam Wilson establishes a memorial to Isaiah’s heroics at the Smithsonian, but the super soldier’s role in Phase 5 will take a dark turn again.

Introduced in Marvel Comics in 2003, Isaiah Bradley was retroactively revealed to have assumed the title of Captain America after becoming a super soldier during World War II following Steve Rogers’ apparent death.

Trailers for Captain America: Brave New World have confirmed that, by some means, Isaiah Bradley will be triggered into attacking the President of the United States. The most popular theory suggests that Isaiah is one of many who are under the control of the Leader, similarly to how the Winter Soldier was under HYDRA’s command for several decades. With the super soldier serum still running through his veins, Isaiah Bradley losing control is a very dangerous concept for the MCU, making him a minor villain in Captain America: Brave New World.

In the most recent trailer for the 2025 sequel, Isaiah Bradley can be seen imprisoned yet again, presumably after his assassination attempt on President Ross. This may provide the motivation for Sam Wilson’s entire journey in Captain America: Brave New World, as he would surely fight to get to the bottom of why Isaiah lost control, which could eventually lead him into the clasps of an even more powerful villain. Isaiah Bradley is one of the most traumatized and troubled characters in the MCU, for good reason, and this may become even worse in Captain America: Brave New World.

2 Samuel Sterns’ Leader

The Leader Will Be Played By Tim Blake Nelson In Captain America: Brave New World

Tim Blake Nelson was confirmed to be returning to the MCU after 17 years in September 2022. Nelson first appeared in 2008’s The Incredible Hulk as Samuel Sterns, a cellular biologist who helped Edward Norton’s Bruce Banner to try and find a cure for the Hulk, though he was ultimately unsuccessful. Sterns also helped to enhance Tim Roth’s Emil Blonsky into the Abomination, and during the final moments of the Phase 1 movie, he, too, was exposed to Bruce Banner’s blood. This began to change the shape of his head, but his fate has been unclear since then.

Fans of Marvel Comics will know that this transformation would have culminated in Sterns becoming the super-intelligent villain known as the Leader. This is the version of the character that Tim Blake Nelson will be bringing to life in Captain America: Brave New World. The Leader appears to be the mastermind behind everything that goes wrong in Brave New World, being the creator of the trigger in Isaiah Bradley, perhaps a benefactor of the Serpent Society, and the cause of President Ross’ transformation into the Red Hulk.

The Leader is one of Marvel Comics’ most iconic supervillains, mainly opposing the Hulk. For the MCU, he will become a Captain America villain, though Captain America: Brave New World does feature many characters associated with Bruce Banner’s Hulk. After 17 years, it will be great to see Tim Blake Nelson back in the MCU, especially since both him and his character have had plenty of time to grow and gain experience. The Leader will likely be a very sinister and enigmatic presence in Captain America: Brave New World, contributing to the movie’s more grounded nature.

1 President Ross’ Red Hulk

Red Hulk Will Be Played By Harrison Ford In Captain America: Brave New World

The most notable villain set to appear in Captain America: Brave New World is, of course, the Red Hulk. Trailers for the Phase 5 movie have confirmed that Thaddeus Ross, who is now the President of the United States, will be transformed into the Red Hulk, following the iconic 2008 storyline of his Marvel Comics counterpart. Ross is now portrayed by Hollywood legend Harrison Ford, who takes over from the late William Hurt, adding even more star power and excitement to Captain America: Brave New World’s already-impressive line-up.

Red Hulk looks fantastic in the trailers for Captain America: Brave New World, raising anticipation for the movie even though the character is not typically a Captain America villain in Marvel Comics. There have been some doubts expressed regarding Sam Wilson’s ability to take on the Red Hulk alone, which perhaps supports theories that either Bruce Banner’s Hulk or a new Avengers team could also appear in the 2025 sequel. There is speculation that President Ross will be turned into the Red Hulk by the Leader, expanding Samuel Sterns’ own influence.

While the Red Hulk shares many of the same powers as Bruce Banner’s Hulk, he also emits a remarkable amount of heat, which makes him far more terrifying than his Avenger adversary. It remains to be seen exactly how Sam Wilson will deal with the Red Hulk in Captain America: Brave New World, but Harrison Ford’s MCU debut as the iconic villain is incredibly exciting nonetheless. There are hopes that the Red Hulk will return in future MCU projects, perhaps even as a member of Marvel’s Thunderbolts team, though this hasn’t yet been confirmed.

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