Oh ffs..
Whether it’s theories or theorists, the document that people typically use to contribute credit to it’s creation is called the Concerning Criticism of the Warren Report written in 1967; which you can read in full here:
http://www.jfklancer.com/CIA.html
“Conspiracy theories have frequently thrown suspicion on our organization, for example by falsely alleging that Lee Harvey Oswald worked for us.”
It neither uses the term “conspiracy theorist” nor “conspiracy theory” and the first known usage was by the American author Charles Astor Bristed, in a letter to the editor published in The New York Times on January 11, 1863 concerning Britain intentions during the American Civil War.
It is highlighted in meme above but for your convenience:
“They only look at the sudden right-about-face movement of the English Press and public, which is most readily accounted for on the conspiracy theory.”
The Warren Report nor do any documents specifically use the term “theorist” or “theory” but rather addresses the theories plural and alleges that they are false.
Further reading:
https://theconversation.com/theres-a-conspiracy-theory-that-the-cia-invented-the-term-conspiracy-theory-heres-why-132117
