The Illuminati is a name given to several groups, both real and fictitious. Historically, the name usually refers to the Bavarian Illuminati, an Enlightenment-era secret society founded on 1 May 1776 in the Electorate of Bavaria. From Wikipedia
The upcoming 'New Thunderbolts'* comic introduces a powerhouse team led by Black Widow and Winter Soldier to combat doppelgangers of the Illuminati.