Ever since rumors about Nathan Fillion joining the cast of "Guardians of the Galaxy 2" came out, fans have been speculating which Marvel character he might play in the film. But recently, thanks to a couple of leaked on-set photos, it seems Fillion's role in the Marvel Cinematic Universe has been confirmed.

These photos which were uploaded by an Imgur user depict a series of fictional movie posters which were used on the set of "Guardians of the Galaxy 2" in Atlanta. Aside from the fact these images point to an Earth setting in the upcoming film, the fake posters feature the face of Fillion playing multiple film roles.

In one of the posters, he is even depicted as Tony Stark, which could be that the promotional material is going to be a biopic based on the billionaire superhero.

But aside from these, Fillion's character in the poster is named as Simon Williams. In the Marvel comic book universe, Williams is the real name of the superhero Wonder Man, who eventually became a member of the Avengers.

According to his fictional biography, he has superhuman strength and speed and the power to manipulate energy. But, even though he's already a superhero and an integral member of the Avengers, he still sought out another life by being an actor in Hollywood. This last detail would definitely explain the movie posters featuring Fillion's face.

But then again, even with these leaked images, it cannot be confirmed yet if Fillion will actually appear in "Guardians of the Galaxy 2." In other words, there's a chance that Fillion may not take on a speaking and acting role in the upcoming film and that these posters could serve as just easter eggs in the movie.

But, whether or not he physically appears in "Guardians of the Galaxy 2," these details clearly suggest that Marvel is prepping Fillion to become a part of the Marvel Cinematic Universe. This could even mean that Wonder Man might get a film of his own in the future.

As for the film, the main cast members such as Chris Pratt, Zoe Saldana, Dave Bautista, Vin Diesel, Bradley Cooper, Michael Rooker, Karen Gillan and Glenn Close are all expected to reprise their roles from the first "Guardians of the Galaxy" movie. The sequel is expected to premiere on May 5, 2017.