Who Is Sidewinder? Captain America 4’s New Villain Explained

Giancarlo Esposito as Sidewinder and Anthony Mackie as Captain America in Brave New World (2025)

Captain America: Brave New World will introduce a new villain named Sidewinder who is taken from Marvel Comics. Captain America: Brave New World‘s story is shaping up to be a big test for Anthony Mackie’s Sam Wilson as he is being put up against a solid roster of villains. Not only does Sam have to face off with the returning Leader from The Incredible Hulk, but Captain America 4‘s Red Hulk will prove an even sterner test for the new leader of the Avengers.

If that was not enough, Giancarlo Esposito was added to Captain America: Brave New World‘s cast recently. It was confirmed that Esposito would play a villain in the movie, though Marvel Studios neglected to reveal who the character is. That is until San Diego Comic-Con 2024, where Screen Rant was in attendance during Marvel’s Hall H panel in which Esposito’s role in Captain America: Brave New World received a spotlight.

Giancarlo Esposito’s Captain America: Brave New World Role Is Confirmed As Sidewinder

A New Villain Is Coming To The MCU

Split image of Giancarlo Esposito in Captain America Brave New WorldImage By Zoe Miskelly

One of the major movie reveals at San Diego Comic-Con 2024 concerning Captain America 4 is that Giancarlo Esposito will portray Sidewinder in the movie. Sidewinder has long been a minor antagonist in Marvel Comics, linked to a supervillain team that has often gone against Captain America. At SDCC 2024, Esposito took to the stage during Marvel’s Hall H panel to talk more about his character, finally revealing the mysterious gunman from Captain America: Brave New World‘s trailer to be Sidewinder himself.

Many theorized that Esposito would play Professor X or Doctor Doom in the MCU before his casting as Sidewinder in Captain America 4.

In Marvel Comics, Sidewinder is connected to the Serpent Society. Back in Phase 3 of the Infinity Saga, Marvel Studios originally teased the Serpent Society to be part of Captain America 3. Although this turned out to be a ploy to hide the fact that the film would adapt Civil War, the Serpent Society will now finally be introduced to the MCU as another foil for Sam Wilson’s Cap, led by Esposito as Sidewinder.

Sidewinder’s Marvel Comics History & Powers Explained

Sidewinder’s Comic History Is Not As Extensive As Other Marvel Villains

Artwork of Sidewinder from Marvel Comics

In the comics, Sidewinder is known as Seth Voelker. The character was originally hired by Roxxon Oil Company to retrieve an artifact called the Serpent Crown, which gave its wearer powers like immortality and the ability to influence minds. Voelker was given a cloak that imbued him with teleportation powers, successfully obtaining the crown before splitting from Roxxon and forming his own group, the Serpent Society. Voelker then recruited several snake-themed villains to his group.

In terms of powers, Sidewinders are fairly limited. One of his biggest assets is his knowledge and intelligence, with Voelker able to turn the Serpent Society into a successful crime organization in little to no time. Regarding actual powers, Sidewinder possesses the ability to teleport using his cloak. This cloak can also teleport others if he covers them with it, linking to his snake-themed name. Finally, Sidewinder can also emit tendrils to attack his enemies, though this comes from his armor rather than an ingrained superpower.

How The MCU May Change Sidewinder For Captain America: Brave New World

The MCU Could Take A More Grounded Approach To The Character Of Sidewinder

Sam Wilson in his new Captain America suit in Captain America Brave New World

In the MCU, Sidewinder may end up looking very different from his comic book counterpart. For one, it is clear from Captain America: Brave New World‘s trailer that Giancarlo Esposito is not wearing the over-the-top, exaggerated costume worn by Sidewinder in Marvel Comics. In the MCU, Esposito is foregoing the snake-themed costume for a more grounded villain look, complete with a black leather duster and shades. This makes a lot of sense considering Captain America: Brave New World is expected to be more akin to The Winter Soldier in tone, another aspect Screen Rant discovered at San Diego Comic-Con 2024.

The grounded tone that Captain America 4 is going for will also likely mean Sidewinder’s connections to the Serpent Society could change. While the Serpent Society may appear in the film, it is unlikely they will have the snake-themed villains present like in the comics. Instead, the group will likely be another corrupt organization akin to HYDRA as opposed to a full-blown supervillain team.

Another change that the MCU could make to the character of Sidewinder is his connection to Roxxon. Thus far in the MCU, Roxxon has not been a massive part of the franchise. As such, it could be the case that Sidewinder is working for another group in Captain America: Brave New World, likely one started by the film’s primary villain, The Leader. These changes to Sidewinder will enable the character to be a more grounded, realistic antagonist for Sam Wilson in Captain America: Brave New World, giving Giancarlo Esposito a similar role to that which made him famous as a fantastic villain from Breaking Bad.

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