I still get a kick out of how Marvel sneaks big reveals into quiet moments — the Illuminati’s formation reads like one of those tightly written secrets. In the comics timeline, the group was retroactively revealed in 'New Avengers' (the big reveal is around issue #7), but in-universe they’re older than that meeting. Tony Stark basically pulled together a handful of the most powerful and influential figures after realizing that heroes weren’t sharing crucial intelligence the way they should. The founding circle usually listed in the comics is Reed Richards, Tony Stark, Namor, Black Bolt, Doctor Strange, and Professor Xavier. Later on, T’Challa (Black Panther) is shown as being involved with them at points too.
They weren’t a fan club — they formed out of fear and guilt. These were characters who’d seen planetary-scale disasters and decided to quietly pool information and make hard decisions
behind closed doors to prevent worse outcomes. That secrecy is the hook: their actions ranged from keeping tabs on alien empires to taking extreme steps like exiling the Hulk into space, which later exploded into the 'World War Hulk' storyline. The group also hoarded dangerous artifacts — the comics reveal they acquired and split up the Infinity Gems at one point, hiding them to avoid another cosmic catastrophe. That choice had ripple effects.
If you want the backstory in comic form, read 'New Avengers' (the Bendis run) for the reveal and the limited 'Illuminati' miniseries that fills in a lot of the retrospective history. For me, the Illuminati are fascinating because they’re a mirror of superhero ethics: brilliant people trying to be pragmatic, and failing in ways that feel human and inevitable.