Giancarlo Esposito in Captain America: Brave New World
(Walt Disney Studios Motion Pictures)

Giancarlo Esposito’s ‘Captain America’ Villain Finally Delivers on a Decade-Old MCU Promise

A new villain is coming to the MCU

After months of leading us on, Giancarlo Esposito has finally unveiled the mystery behind his Captain America: Brave New World character. So who is Sidewinder, and why is his introduction to the Marvel Cinematic Universe so important?

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On Saturday, Marvel Studios took to San Diego Comic-Con’s Hall H for its annual panel, with this year’s focus being on three 2025 releases: Captain America: Brave New World, Thunderbolts, and the MCU Fantastic Four reboot. To fans’ mutual joy and horror, President Kevin Feige announced that the Russo Bros. would return to helm the next two Avengers projects, Avengers: Doomsday and Avengers: Secret Wars, before bringing out Robert Downey Jr. to announce his casting as Doctor Doom. It’s complicated.

But one of the highlights was seeing the cast and crew of Captain America: Brave New World take to the stage, with an especially chaotic Anthony Mackie throwing F-bombs at Tom Holland, Harrison Ford Hulking out, and the film’s (sadly, COVID positive) director, Julius Onah, dropping exclusive new footage for attendees. The fourth Cap entry has been described as a grounded Winter Soldier-esque political thriller, and the teaser clip certainly backed this up, showing Sam Wilson working alongside the US Government and President Thaddeus Ross to “rebuild” the Avengers.

Who does Giancarlo Esposito play in the MCU?

Along with answering our burning questions about the fallen Celestial from Eternals (which was confirmed to be made of Adamantium), the Brave New World footage also showed Giancarlo Esposito’s character rocking aviators—and a whole lot of guns—as he goes up against Sam. So who is he exactly?

Well, according to Esposito, who was there in person for the Hall H panel, he’ll be playing Serpent Society founder Seth Voelker, a.k.a. Sidewinder.

At SDCC, Esposito shared some new insights into his Brave New World character, telling the audience, “He’s a complicated guy who didn’t start in a nefarious way. He came to this in a different way, which hopefully will unfold. And I like it because you’ve seen me play certain villainous characters who use their brains, who are great at dictating what to do and how to do it.” Giancarlo Esposito, playing a villain? Nooooo. Who would’ve thought!

Captain America: Brave New World might finally bring the Serpent Society to the MCU

Since Esposito popped up in the first trailer, speculation has run rampant about who he could be playing in Brave New World, with a popular theory being that he would introduce S.H.I.E.L.D. agent and former Six Pack member G.W. Bridge to the MCU. However, that’s clearly not the case, as he’ll be taking on the role of the somewhat obscure Captain America baddie Sidewinder instead.

A former economics professor-turned-mutant by the Roxxon Oil Company, Sidewinder was first introduced in Marvel Two-in-One #64 in 1980. In the comics, he went on to form the Serpent Society, which, as the name suggests, is a group of snake-like criminals and vigilantes.

Still, fans shouldn’t get their hopes up about a beat-for-beat adaptation of the Marvel comics, as the Brave New World teaser suggests that we’re going to see a different kind of Serpent Society in the MCU—perhaps, something more akin to a terrorist organization like HYDRA. We also haven’t seen Sidewinder whipping out his teleportation cloak yet, so who knows? Maybe he’ll just be your average, run-of-the-mill bad guy, not necessarily a super-powered villain—that honor will likely go to Tim Blake’s The Leader. But Sidewinder’s combat expertise and influence make him a formidable foil for Cap, so we definitely shouldn’t underestimate him either.

What is Sidewinder’s MCU future?

Well, with the MCU’s Phases 5 and 6 being all about the Multiverse, there might not be room for street-level antagonists (or so we think) in future Avengers installments. However, Sidwinder’s status as a mutant does distinguish him from some of our other villains, given Feige recently teased that Deadpool & Wolverine is “just the beginning” for mutants in the MCU. 

So, is Marvel finally bringing the Serpent Society to life after teasing that the group would play a pivotal role in Captain America: Civil War nearly a decade ago? It’s hard to say, but Sidewinder’s MCU introduction is certainly promising. Either way, Sam and his allies are going to have quite a few foes in Brave New World, from Esposito’s character to Ford’s Red Hulk and everyone in between. It’ll be interesting to see how it all goes down when the action flick hits theaters in February 2025.


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Amanda Landwehr
Amanda is a Los Angeles-based entertainment writer who lives and breathes Star Wars, Marvel, and all things pop culture. She has worked in digital media since 2021, covering the latest movie/TV releases, casting updates, fan theories, and so, so much more. When she's not rotting away behind her laptop screen, you can typically catch Amanda maxing out her AMC Stubs membership.