With the Fantastic Four and X-Men film rights presumably coming back to Marvel as part of the Walt Disney Company acquisition of 21st-Century Fox, the House of Ideas is one step closer to having full control of all of its characters.
Today's agreement provides Disney "with the opportunity to reunite the X-Men, Fantastic Four and Deadpool with the Marvel family under one roof and create richer, more complex worlds of inter-related characters and stories that audiences have shown they love," read the official announcement.
But there are still some Marvel properties outside the ever-growing Disney bubble.
Under the terms of a 2015 deal, Marvel Studios obtained permission to make Spider-Man films (for Sony) and use some of its characters in the Disney-produced Marvel Studios films. But key in that deal is that Sony retained its full ownership of those rights, for Spider-Man and its associated characters, as well as those under its umbrella that it's developing for solo movie projects such as Venom, Silver and Black, Morbius and the animated Spider-Man: Into the Spider-Verse.
Univeral Pictures has the distribution rights to the Hulk franchise, which include characters like Bruce Banner/Hulk, Betty Ross, General Ross, Abomination, She-Hulk, and the Leader. Marvel can utilize these characters to a degree in other projects, but any movie with these characters squarely in the lead role would have to be done in partnership with Universal - and players involved say that isn't going to happen.
"I wanna make just one thing perfectly clear today, a standalone Hulk movie will never happen," Mark Ruffalo told Variety in July 2017. "For some reason [Universal doesn't] know how to play well with Marvel... because they don't want to make money."
2008's Incredible Hulk film was made in a partnership by Universal and Marvel Studios, but the two sides have been unable to come to terms on anything similiar since the success of 2008's Iron Man.
In a similiar situation, the rights to Marvel Comics' earliest character Namor are also tied up in rights situations. Marvel Studios' president Kevin Feige previously said that any Namor film would have to include Marvel Studios but that the film rights are owned by other parties including Universal (which optioned the character in 2001).
"Let’s put it this way - there are entanglements that make it less easy. There are older contracts that still involve other parties that mean we need to work things out before we move forward on it," Feige told IGN. "As opposed to an Iron Man or any of the Avengers or any of the other Marvel characters where we could just put them in."
That being said, Universal has sold rights back to Disney before - in 2008 a deal was made for Disney's Oswald the Lucky Rabbit to rejoin Disney (in exchange, oddly enough, for a football announcer).
Prior to Disney's acquisition of Fox, Marvel re-acquired the rights to Daredevil (from 20th Century Fox), Punisher (from Fox), Blade (from Warner Bros./New Line Cinema), Ghost Rider (from Sony) and Man-Thing (from Lionsgate) going on to use all to varying degrees for television and animated projects.
And in addition to all that, Marvel Entertainment owns both Men In Black and the Ultraverse - acquired as part of its purchase of Malibu Comics in 1994. Columbia Pictures, Amblin Entertainment and Malibu Comics co-founder Scott Rosenberg retained the lucrative film rights to Men In Black however, and rights to the Ultra characters remain murky.
"Let's just say that I wanted to bring these characters back in a very big way, but the way that the deal was initially structured, it's next to impossible to go back and publish these books," Marvel Chief Creative Officer Joe Quesada told Newsarama in 2005. "There are rumors out there that it has to do with a certain percentage of sales that has to be doled out to the creative teams. While this is a logistical nightmare because of the way the initial deal was structured, it's not the reason why we have chosen not to go near these characters, there is a bigger one, but I really don't feel like it’s my place to make that dirty laundry public."
That being said, New Line Cinema owned the rights to an Iron Man movie until 2005 - and Marvel Studios made that work pretty well.