Guess Which TV Star is Making a Surprise Visit to the 'Galaxy'

Nathan Fillion may be returning to space. The fan-favorite TV star — who just finished his seventh season on ABC’s Castle — will appear in the upcoming Marvel superhero movie Guardians of the Galaxy.

In a recent tweet, Galaxy director James Gunn confirmed that the actor will have a “very fun small cameo,” joining a cast that includes Chris Pratt, Zoe Saldana, Vin Diesel, and Bradley Cooper.

That Fillion has been given a role at all is a matter of great excitement to a large segment of sci-fi fans. While best know for playing a sleuthing mystery novelist, Fillion has serious geek cred — a lot of which comes from his long association with Joss Whedon: the actor had a recurring role on Buffy the Vampire Slayer and meaty part in the hugely popular online series Dr. Horrible’s Sing-Along Blog (2008). But it was through his portrayal of Captain Malcolm Reynolds on the 2002 sci-fi-Western Firefly that Fillion achieved geek-hero status.  

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Gunn — who directed Fillion in the 2006 horror-comedy Slither — divulged few details about the role, though he made a point of shutting down rumors that the actor would play a character named Nova. Is there a possibility Fillion pays sort of homage to Firefly's beloved Captain Malcolm Reynolds?  Let the newest round of rumors begin …

Guardians of the Galaxy opens August 1, 2014.

Photo: Fillion and Gunn by Kevin Winter/Getty Images