It is finally happening. After years of speculation, missed opportunities, and leaked set photos that became the stuff of legend, Marvel is actually giving us a Wonder Man series. But there is a giant, purple, ionic elephant in the room. If you head over to Disney+ on January 27, 2026, to watch the premiere, you aren't going to see Nathan Fillion’s face under the mask.
Instead, Yahya Abdul-Mateen II is the man leading the charge as Simon Williams.
This has left a lot of people—mostly those who grew up on Firefly or spent too much time on mid-2010s message boards—feeling a bit confused. Wasn't Nathan Fillion already Wonder Man? Didn't we see the posters? Honestly, the history of Nathan Fillion as Wonder Man is one of the weirdest "almost" stories in the history of the Marvel Cinematic Universe (MCU). It’s a tale of deleted scenes, meta-commentary, and a very specific type of fan-casting that actually came true, only to be snatched away.
The Guardians of the Galaxy Vol. 2 Incident
Let's go back to 2017. James Gunn, a man who loves his friends almost as much as he loves obscure 70s rock, was filming Guardians of the Galaxy Vol. 2. Reports started leaking from the set in Cartersville, Georgia. People saw a movie theater marquee. It was advertising a "Simon Williams Film Festival."
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There they were. Giant, glossy posters featuring Nathan Fillion in various hilarious roles: a romantic lead in Oh, Rebecca, a gritty action star in Toxic Janitor, and, most importantly, the title role in a biopic called Arkon. In Marvel lore, Simon Williams is a superhero who eventually gives up the "world-saving" thing to become a Hollywood actor.
James Gunn wasn't just throwing a bone to fans; he was literally casting Fillion as the MCU’s Simon Williams.
Then the movie came out. We all sat in the dark, popcorn in hand, waiting for the Earth-based scenes. And... nothing. The entire sequence was cut. The posters never made it to the big screen. Gunn later explained that the pacing of the movie just didn't work with a detour to Earth, so the "Fillion as Wonder Man" cameo was relegated to the cutting room floor and behind-the-scenes Facebook posts.
Why Nathan Fillion Was the Perfect Simon Williams
It’s easy to see why the internet was obsessed with this. Simon Williams, in the comics, is kind of a jerk. He’s charming, yes, but he’s also deeply insecure, slightly arrogant, and has that "fading leading man" energy.
Nathan Fillion basically built a career on that exact vibe.
Think about Captain Tightpants himself, Malcolm Reynolds. Or the suave, slightly buffoonish Richard Castle. Fillion has this uncanny ability to play a guy who thinks he’s the smartest person in the room while simultaneously being the most relatable. That is Wonder Man. He’s the guy who would go on a talk show to promote a movie while an alien invasion is happening three blocks away.
For a long time, it felt like a missed opportunity. Even after the cameo was cut, Gunn kept the hope alive, saying he hoped Simon Williams would "rise again." But as the MCU shifted toward Phase 5 and Phase 6, the vision for the character changed.
The 2026 Reality: Yahya Abdul-Mateen II Takes Over
So, why isn't Nathan Fillion the lead in the new 2026 series?
Basically, it comes down to the direction of the story. The new Wonder Man series is being described as a "meta-comedy" and a "satire of Hollywood." While Fillion is the king of that tone, the MCU producers—including Shang-Chi director Destin Daniel Cretton—wanted a version of Simon Williams who was just starting his journey.
Yahya Abdul-Mateen II brings a different kind of intensity. He’s playing an aspiring actor who auditions for the role of Wonder Man in a fictional movie within the MCU. It’s a layers-deep concept. The show explores the "Doorman Clause," a fictional legal rule in the MCU that prevents superpowered people from working in Hollywood.
Interestingly, the show doesn't completely ignore the past. There are heavy rumors (and some very meta-teasers) suggesting that the "original" Wonder Man movies from the MCU's history—the ones Fillion starred in on those posters—might still exist as in-universe cult classics.
The DC Pivot: From Ionic Energy to Green Lantern Rings
If you’re a Fillion die-hard and you’re still mourning the loss of his Marvel career, don't worry too much. He’s doing just fine. While Marvel was busy rebooting Simon Williams, James Gunn was busy taking over DC Studios.
Almost immediately, Gunn brought his buddy over to the "other side."
Fillion is currently playing Guy Gardner, the most abrasive and bowl-cut-sporting member of the Green Lantern Corps, in the 2025 Superman movie. It’s a role that actually shares a lot of DNA with Wonder Man. Guy Gardner is a loudmouth, overconfident, and frequently annoying hero who somehow still manages to do the right thing.
It’s the role Fillion was born to play. Honestly, seeing him with that 90s-style bowl cut and the green tactical vest is probably a better use of his comedic timing than a standard Marvel lead role would have been at this stage of his career.
What to Expect from Wonder Man in 2026
The Wonder Man series arriving this January is going to be weird. Really weird. It’s dropping all eight episodes at once, which is a rare move for Marvel—usually they only do that for "Spotlight" series like Echo.
- The Trevor Slattery Connection: Ben Kingsley is back. He’s playing a mentor/frenemy to Simon Williams, which pretty much guarantees the show will be more about the absurdity of acting than the physics of "ionic energy."
- The Tone: Expect something closer to Barry or The Larry Sanders Show than The Avengers.
- The Nathan Fillion Legacy: Keep your eyes peeled for Easter eggs. Even if he isn't the star, the production team knows how much fans loved those 2017 posters. Don't be surprised if a "Simon Williams Film Festival" DVD ends up on a shelf in the background.
Actionable Insights for Fans
If you're trying to keep up with the shifting landscape of superhero casting, here is the "too long; didn't read" of the situation:
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- Watch the 2026 Series for the Meta-Humor: If you go in expecting a traditional action show, you'll be disappointed. This is a satire about being an actor in a world where gods and aliens are real.
- Check out the DCU for your Fillion fix: If you want to see Nathan Fillion playing a high-budget superhero, the new DC Universe is where he’s officially landed.
- Revisit the GOTG 2 deleted scenes: To see what could have been, look up the "Simon Williams Film Festival" posters online. They are a masterclass in visual storytelling and a reminder of how much fun James Gunn has with the medium.
The story of Nathan Fillion and Wonder Man is a reminder that in the world of comic book movies, nothing is ever truly wasted. A cut cameo in 2017 paved the way for a meta-masterpiece in 2026, and one of our favorite actors finally got a ring—it just happened to be a green one.