User:TG90/20th Century Fox's owned Marvel properties

Due to the fact that 20th Century Fox exclusively owns the film rights to almost any X-MEN and Fantastic Four related property since 1994, none of such characters can appear or even be mentioned in the MCU. Though there are some specific Marvel characters, whose film rights are actually shared between Marvel Studios and Fox, being some of the few odd exceptions to the rule. Nevertheless, the cinematic separation of such properties from the rest of the Marvel universe has greatly influenced the mainstream Marvel comic books.

X-MEN
On May 1st, 2013, during the pre-production of Avengers: Age of Ultron, director and writer Joss Whedon revealed that he included into the script a "brother/sister act" from the comic books. On May 17th, 2013, it was officially announced that those comic book characters, who would make their debut in the MCU, were Quicksilver and Scarlet Witch. Due to the characters' long history in both X-Men and The Avengers titles in the comic books it was revealed that Marvel Studios shares their film rights with Fox.

Because of that any conflict with Fox's X-Men films had to be avoided. A new origin story was introduced for the twins, that did not involve their biological father |Erik Lehnsherr a.k.a. Magneto and their status as | mutants or even any mention to those elements, as for the MCU, they are considered non-existent. As a consequence, Whedon was able to introduce two major characters into the MCU completely on his terms for the first time.

"It allowed me to tie their origin into the mythos of this [MCU] universe more effectively," said Whedon. "It’s more useful to me than introducing the idea of mutants."

In Age of Ultron, Wanda and Pietro Maximoff are simple humans born in the Eastern European country of Sokovia, who get genetically altered and gain super powers, in a series of tests, run by the terrorist organization HYDRA, involving the Infinity Stone, contained in a Chitauri scepter.

With Pietro and Wanda's introduction to the MCU with a new backstory, changes to their comic book counterparts were not far behind. In Avengers & X-Men: AXIS #7 (2014), it was revealed that Pietro and Wanda have no actual blood ties with Magneto. In Uncanny Avengers #4 (2015), it is confirmed not only that Magneto is not their biological father but the twins are not even mutants, as the High Evolutionary genetically altered them as infants, giving them their powers, before returning them to their true parents, the Maximoffs.

Expansion of the INHUMANS
The X-Men and the mutants in general, are a big part of the Marvel comic book universe. Their inevitable absence from the MCU, has caused a lot of speculation regarding their possible replacement by another, previously lesser known, Marvel comic book property, the Inhumans.

The Inhumans were eventually introduced in the MCU in the TV series, Agents of S.H.I.E.L.D. A live-action film, adapting this same property, was announced to be released on July 12, 2019.

Prior to the release of Age of Ultron, it was speculated that the Scarlet Witch and Quicksilver would be introduced as Inhumans, therefore explaining the emerge of their superhuman powers. These reports were eventually denied by Marvel Studios' President Kevin Feige.

"Inhumans is something that we are definitely thinking about and we think there's great potential there for a great movie. But, no, no -- we have not linked those two." When Feige was asked if using the Inhumans has something to do with getting around the word "mutant", he responded: "As it relates to Scarlet Witch and Quicksilver? No. No, no, no."

Fantastic 4
Coming soon