Marvel Studios has built an empire using characters that were once considered B-list, because many of its A-players had been licensed out to other studios, including Fox.

Now for the first time, the studio's cinematic universe will have access to classic characters that were once key pillars to the publishing division. Fantastic Four is the comic that launched Marvel, while X-Men was the best-selling and most influential comic title for over two decades.

The injection of new characters comes as Avengers: Endgame will presumably be the swan song for some of the characters who have turned from heroes largely unknown outside of comic book circles to the faces of billion-dollar franchises, such as Chris Evans' Captain America and Robert Downey Jr.'s Iron Man.

Reynolds' Deadpool is expected to be the only iteration of the X-Men to make the jump to Disney, with Disney CEO Bob Iger having confirmed multiple times that a popular, R-rated version of the character could exist at the studio.

But before it reboots the X-Men, Disney is inheriting two projects from Fox. Dark Phoenix (June 7) will be the first X-Men movie marketed by the studio and comes from longtime X-Men producer Simon Kinberg, making his directorial debut.

The fate of the other film, writer-director Josh Boone's New Mutants, remains in the hands of Disney execs, who will decide its future after seeing it. New Mutants still has an Aug. 2 release date, but is said to be troubled. The idea of reshoots has been brought up, although the film could ultimately end up on a streaming platform, such as Disney+ or Hulu rather than a theatrical release.

Charting a path forward for the X-Men isn't the only challenge faced by the integration. The X-Men films date back to 2000's X-Men, and there are producer deals that will need to be looked at and either untangled or bought out, say sources. Lauren Shuler Donner, who championed the 2000 film and has been a producer on all Fox's mutant-centric movies, is said to have a deal that calls for her to receive an executive producer credit on any X-Men movie whether or not she is actively involved. Kinberg may have a similar deal.

Marvel Studios has not publicly revealed any plans for integrating members of the X-Men and Fantastic Four into its cinematic universe, though Marvel Studios head Kevin Feige is said to have met with several members of the X-Men old guard in recent months. Fargo showrunner Noah Hawley, who was hired to write a Doctor Doom movie in 2017, earlier this month confirmed he's spoken to Feige about the script centering on the Fantastic Four villain, though Hawley downplayed how serious those discussions were.

Though the Marvel projects will be under the purview of Feige, who has worked on Marvel properties since 2000's X-Men, genre-based special effect-laden extravaganzas will still be made at Fox. In early January, Fox greenlit its last batch of pre-Disney acquisition movies that are now beginning to go into production and will be overseen by Disney brass on some level. Fear Street, based on the R.L. Stine books, began shooting a couple of weeks ago. Free Guy, which stars Reynolds as a man who realizes he's living in a video game movie, has Shawn Levy set to direct and begins shooting next month.

Mouse Guard, based on the Boom! Studios comic series, is a motion-capture franchise starter being produced by Matt Reeves beginning in May. Steven Spielberg’s take on West Side Story is to begin shooting this summer while Death on the Nile, the follow-up to Murder on the Orient Express, is prepping for a late September start with Kenneth Branagh back as detective Hercule Poirot and Gal Gadot and Armie Hammer on the suspects list.

Marvel has just one movie officially dated and titled for after Endgame — July's Spider-Man: Far From Home, a co-production with Sony Pictures. While Disney's release schedule does contain the highest volume of untitled Marvel movies yet (two in 2020, three in 2021), it remains unclear when an X-Men or Fantastic Four movie could make it onto the calendar. Marvel is expected to shoot Black Widow and The Eternals this year, with kung fu hero Shang-Chi likely to bring up the rear. Also in development are sequels to Black Panther, Doctor Strange and Guardians of the Galaxy Vol. 3. Unless Feige has a completed script waiting in his desk drawer, any of the newly arrived heroes are unlikely to hit screens at least until 2021, if not later.