Ok, so Sony has Spider-Man (kind of), Fox has The Fantastic Four and X-Men. That means that most of the characters that are attached to these respective properties belong to those studios. Right? Well... there are exceptions.
When Marvel announced that the Krulls, a Fantastic Four species of villains were going to appear in the upcoming Captain Marvel film people (including me) were confused. Thankfully, Guardians of the Galaxy Vol. 2 director answered that question... actually back in 2016. It seems that while specific Skrulls are owned by Fox still the entirety of the species is co-owned.
Some specific Skrulls are at Fox. But the Skrulls as a whole are co-owned. https://t.co/2hJYkskLZ3— James Gunn (@JamesGunn) July 6, 2016
This isn't the first time that Gunn has done some clarifying for Marvel fans. This time he did it on facebook:
As we reported back in 2015:
The Shi'ar are likely linked to Fox's X-Men rights, since the avian empire was introduced in the pages of X-Men. They're also intertwined with the mythology of the Phoenix Force, which has frequently taken possession of Jean Grey and other of Earth's mutants. The original "Dark Phoenix Saga" culminated with an epic battle between the Shi'ar Imperial Guard and the X-Men, with Jean's life hanging in the balance.
Kang the Conqueror has been a nemesis to both the Fantastic Four and the Avengers. He first appeared as Kang in an issue of Avengers from 1964, but appeared as Rama-Tut in an issue of Fantastic Four a year earlier. What likely solidifies him under the Fantastic Four film rights is the fact that his alias is Nathaniel Richards, and that he is a distant future relative of Reed Richards.
Captain Marvel will be released March 8, 2019 and will star Brie Larson.