Warning: This contains potential spoilers for Marvel's Guardians of the Galaxy.

If Nathan Fillion isn't making a cameo as Nova or Cosmo in Marvel's Guardians of the Galaxy, then who is he playing? Although both the actor and director James Gunn have remained tight-lipped, Stitch Kingdom appears to know the answer to that and much more.

The Disney news site reports it has been provided with the full credited cast list for the space adventure, which reveals that Fillion will play "Monstrous Inmate" -- Gunn did say it's "a very small cameo" -- while Stan Lee makes an appearance as "Xandarian Ladies Man." Gunn gets some screen time as "Maskless Sakaaran," and Rob Zombie voices "Ravager Navigator Voice." Fred the dog has his day as Cosmo, chief of security on Knowhere, the enormous floating head of a Celestial that serves as an interdimensional crossroads, port of call, and home base for the Guardians.

However, the biggest surprise may be the acknowledgement of Steve Gerber and Val Mayerik, creators of Howard the Duck, which would seem to suggest the character makes an appearance in the film. Stitch Kingdom notes that it might be a nod to a movie or comic that Peter Quill was familiar with before he was abducted from Earth. Of course, Howard could simply be an Easter egg tucked into a crowd scene in Knowhere's marketplace or bar.

Whatever the case, we'll know for sure when Guardians of the Galaxy arrives Aug. 1.