The issue of rights can get a bit muddled when we examine the minutiae, but Guardians of the Galaxy director James Gunn recently revealed that one very important corner of the Marvel mythos is co-owned by both FOX and Marvel Studios: Skrulls.
While most Marvel characters currently reside in the Marvel Cinematic Universe, FOX continues to maintain a vice grip on plenty of other vital properties.
Any major fan of the Marvel universe will instantly tell you that there exists one major flaw with the current plethora of movies based upon Marvel characters: the source material has become split down the middle.