Chiwetel Ejiofor is known for his roles in 12 Years a Slave, The Old Guard, Maleficent: Mistress of Evil, The Martian, Salt, and Love Actually. Iron Man, Professor Charles X, Mister Fantastic, Black Bolt, Namor, king of Atlantis, and Doctor Strange are some of the founding members of the Illuminati in the comics. While the shared universe has brought a number of characters from the comics, the Fantastic Four and the X-Men have remained on the sidelines and in their own separate universe because they didn't own the rights to adapt them to the big screen. The telepath and founder of the X-Men appeared in a lot of the movies. In the film, Mordo replaces Doctor Strange in the group after Strange went rogue and decided that he would use the powers of the Darkhold on his own. In Doctor Strange in the Multiverse of Madness, every member of the Illuminati is portrayed, their powers, and how their live-action adaptation differs from the source material.
After appearing in Captain America: The First Avenger and other films, as well as the short-lived series Agent Carter, Peggy has since appeared in other films and TV shows. The strength of Scarlet Witch's magic, which could manipulate reality and manipulate so many elements with barely a flick of her hands, was too much for the Illuminati. Inhumans and Doctor Strange in the Multiverse of Madness are the series in which Black Bolt was last seen. She is known for her roles in The Pillars of the Earth and Conviction. Maria was the best friend of Carol and the founder of the S.W.O.R.D. before she died of cancer. When faced with an enemy who can do anything and will go to great lengths to accomplish her goal, the superhero group's power is limited. Though they are not a part of the shared universe's primary Earth, their appearances create a shift in the status quo while leaving the door open for opportunities to see them again at some point in the future. The X-Men, Fantastic Four, and Deadpool properties were all under the umbrella of the MCU, but they had yet to be integrated into its films and TV series.
In Doctor Strange in the Multiverse of Madness, the founding members of Earth-838 are different than in the comics. Krasinski is best known for his roles in The Office and Jack Ryan. Iron Man, one of the founding members of the Illuminati, realized that other powerful superheroes on Earth knew of things they could have shared with him and others in a bid to prevent the war from causing further damage. In the film, it's not clear if the MCU's version of the Illuminati is the original or if they've already been rotating members. Monica, Maria's daughter, is not mentioned in Doctor Strange in the Multiverse of Madness. Doctor Strange 2 doesn't establish at what point the Illuminati formed and why, which is different from the thought-out reasoning of the comics.
The Illuminati of Earth-838 were introduced by Doctor Strange in the Multiverse of Madness. In order to keep each other informed and to make decisions regarding what to do about certain issues and conflicts, a secret society of superheroes was formed.
The Kree-Skrull War was a war between two beings that affected Earth. Reed Richards and Professor X are in Doctor Strange in the Multiverse of Madness for the first time. Star Trek: The Next Generation and Star Trek: Picard are also included.