The Illuminati has always been considered (or to me at least) to be one of the most common knowledge conspiracy theories of all time, with them simply being known as the monsters in the shadows that pull all the strings across the world, causing disaster after disaster, incident after incident, using every living being to their advantage, all under the banner of the “All Seeing Eye”.
However, the Illuminati have never always been this elitist group that everyone nowadays believes them to be. After some research, I found that the Illuminati, while indeed was a secret society, was far less powerful or even dangerous than one would have you believe. Originally the Illuminati were secret group of wealthy/successful men who wished to create a world free of superstitious, religious control and abuse of state power, something that most would agree being quite heroic in a way. Their symbol was not even the all seeing eye (which was likely the product of modern depictions by theorists), but rather the Owl of Minerva, a great symbol of knowledge.
The group was founded in 1776 and led by Adam Weishaupt, who acquired a fair few followers over the lifetime of his order before its miserable collapse and take-down in 1785, when the government discovered and banned the secret society, and all others after the internal structure and member relations of the group began to fall apart and resulted in their discovery to the whole world.
After that the group disappeared completely, although that has yet to stop people from believing that the group, under new leadership and goals, has survived and grown over the centuries with the aim of world domination. Many more dedicated theorists also believe that members of the group are devil worshipers and possess high levels of technology and resources.
Due to it possibly being the theory which I have the most common knowledge about, I will most definitely try to use the Illuminati for my final piece, also due to the amount of possibilities in terms of what I could do with the design (e.g. all seeing eye).