By Darren Franich
Updated June 23, 2014 at 06:53 PM EDT
Credit: Science Channel

Before Nathan Fillion became the star of ABC’s ridiculously successful Castle, Nathan Fillion was the star of many things that were less ridiculously successful but possibly even more beloved by Fillion partisans. This was the era when Fillion became a regular presence in the films of James Gunn, taking a starring role in 2006’s slimy-alien film Slither and a smaller-but-hairier role in 2010’s Super. Suspicion ran high that Fillion would have some kind of role in James Gunn’s Guardians of the Galaxy, especially since the movie had already cast fellow Gunn regular Michael Rooker as a blue man with a red mohawk.

And now, wonder of wonders, Gunn has confirmed the rumors on Twitter:

Given that Gunn specifically notes that Fillion’s cameo is “very small,” it’s unlikely that Fillion is playing a major character from the cosmic Marvelverse. Like, he’s probably not Adam Warlock. Unless he is Adam Warlock? Below, the 12 best guesses off the top of my head for who Fillion is playing in Guardians of the Galaxy:

1. Charlie-27, old-school Guardian of the Galaxy. Suitably lame enough to be introduced and then killed off immediately.

2. The father of Chris Pratt’s Peter Quill, in flashback.

3. Thanos, but specifically, a Skrull that’s imitating Thanos, and when the Guardians realize it’s not really Thanos, he turns into Nathan Fillion with green skin and says something kind of funny and endearing before having his head blown off.

4. Starfox, a.k.a. Eros, brother of Thanos and ladies’ man layabout. He’s basically Guy Pearce in The King’s Speech. Also feels like the kind of secretly deconstructive over-the-top jock role that Fillion knocks out of the park.

5. Eternity, the anthropomorphized representation of everything that ever is or was. (For appropriate symmetry, Elizabeth Banks should play Infinity.)

6. The voice of a funny robot.

7. The voice of another raccoon who isn’t Rocket Raccoon.

8. The voice of Ego the Living Planet.

9. The Beyonder. See also Charlie-27: A character that some people know who is so fundamentally goofy that it would only make sense for Marvel to include them as a subtle nod to the High Nerds in the audience.

10. A rare alien help captive inside of the Collector’s museum. Let’s say he has red skin; nobody has red skin yet.

11. An unidentified guy hanging out at a bar, wearing a brown coat over suspenders, who as a quick throwaway line about how he would like to achieve serenity, and then he swats away at a firefly.

12. A gardener who is surprised to discover that his garden has grown a new tree overnight. This tree turns out to be Groot and they have a nice little conversation. The Fillion-Gardener is wearing green and holding a lantern, because in-jokes.

Guardians of the Galaxy

  • Movie
  • PG-13
  • 122 minutes
  • James Gunn