Board Thread:Questions and Answers/@comment-5933274-20150905203757/@comment-16461120-20151022195817

During an interview promoting the European premiere of original Avengers film, MARVEL Studios President Kevin Feige stated that rights to the Skrulls are owned by both FOX and Disney, and either studio could use them in their films. (Although he did not say so, it would not be unreasonable to believe that the Skrulls centuries-old enemies the Kree, who also factored heavily in many Fantastic Four and Avengers storylines, were under the same shared agreement.) Furthermore, Feige did not clarify the status of one particular Skrull character, the so-called Super-Skrull, who has all the powers of the Fantastic Four in addition to his native shape-changing ability, though it is generally believed that the rights lie solely with Twentieth Century FOX.

Universal have relinquished the live-action production rights to Namor by failing to create a film; however, as is the same situation with Hulk, Universal still retains the live-action distribution rights to the characters, and their contract concerning the former also has some language regarding digital reproduction rights, so Disney would have to pay royalties to Universal for including Namor in video games. (This is why we likely won't get another stand alone Hulk film until that situation expires, because Disney is not interested in paying 100% of the production costs in order to have to share the resultant revenues when other properties aren't shared.)

Lastly, the X-Men rights have different nuances than either the Fantastic Four or Namor, and despite the rumored feud between FOX and Disney, the two studios work together more than the conspiracy theorists care to admit, as evidenced by the fact that Disney is heavily promoting the Deapool film, which Kevin Feige is an executive producer on, plus Disney is expanding the live-action agreement beyond films to allow FOX to make television shows, something that's not accounted for in the original contract.