Nathan Fillion might not have been kidding when he told a St. Louis Comic-Con crowd that he will be in Guardians of the Galaxy.

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The former Firefly star clearly has connections to Marvel's big damn hero - Joss Whedon - but Fillion also stared in James Gunn's Slither. With Gunn now at the helm of Guardians of the Galaxy, one Comic-Con attendee asked Fillion if he wanted to snag a role in the upcoming galactic adventure.

"Wanting to? Or maybe, did?" Fillion answered enigmatically, according to IGN. "I'm just sayin' maybe. Maybe there'll be a surprise. Maybe check the credits after the movie when you watch it."

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While some fans sloughed off statement as a joke, a recent tweet from Gunn may prove that Fillion wasn't just messing around.

"There is a cat running around my office let out of his respective bag. I have a feeling @NathanFillion has been in here," Gunn lamented on Monday.

However, it sounds like only the most eagle-eyed of viewers will be able to spot the Castle actor. When Fillion told fans to check the credits, he was probably referencing the fact that his role is tiny and probably covered by layers of makeup.

Guardians of the Galaxy will hit theaters on Aug. 1. Click the video below to see a new trailer for the Marvel film.

Tags: Guardians Of The Galaxy Marvel Movies Nathan Fillion