A mysterious source within Marvel has confirmed that Nathan Fillion will be Richard Rider, AKA Nova. I have been beating this drum for months. If this information proves legit, I am calling a major I-told-you-so-internet. Of course, it’s not for sure, but the evidence is building up.
There is this source. There is Fillion’s hinting that he would be in the post credits of Guardians. There is the heavy use of the Nova Corps in the movie.
I think it’s legit. Of course, for now, only time will tell.