Figuring out what characters Marvel can and can’t use in its cinematic universe has always been a bit of a messy venture. The shapeshifting Skrulls are just one of many sets of characters whose rights are in contention—but Guardians of the Galaxy director James Gunn has cleared up their situation a little bit.
Source: io9 – Marvel Studios Still Has Cinematic Rights to the Skrulls—Just Not All of Them