The Marvel Comics version of the Illuminati was introduced by comic book writer Brian Michael Bendis and consisted of heroes like Iron Man, Professor X, Namor the Submariner, Black Bolt, Doctor Strange, and Mister Fantastic. Not only were they responsible for sending The Hulk into outer space (leading to World War Hulk), but they also interfered in a number of big events.
Simply put, they pulled the strings of everyone in the Marvel Universe, and came across in an almost villainous light on occasion. It proved to be a fascinating concept, and a group of bad guys known as the Cabal was later established to counter them (made up of names like Norman Osborn, Doctor Doom, and Loki).
The usually very reliable folks over at The Illuminerdi are reporting that they've seen a cast listing revealing that a project of some sort revolving around the Illuminati is in the very early stages of development.
It's unclear whether this is a movie or TV show, but it's hard not to get excited about what it could mean for the Marvel Cinematic Universe, and which characters will be assembling to secretly control this shared world. What we do know is that Iron Man won't be a member after his death in Avengers: Endgame. There is, however, plenty of potential for the other team members.
It could be a while before we hear anything official, but we'll be sure to keep you guys updated!