Not a "who" but a "what".
Whoever invented Qanon, claimed to be a US geovernment or military officer with access to very high-level information whose security level code is the letter "Q".
A little thought will show the claim to be absurd. If it was true the relevant authorities would have flushed him or her out long ago as a danger to security, even if no information had been compromised.
BBC Radio Four ran a long investigative series, The Coming Storm, by its Washington correspondent Gabriel Gatehouse, trying to establish Qanon's source and its development into a sort of movement.
He was among the many US and overseas correspondents covering President Biden's inauguration, only for all to be taken by surprise by a bunch of Trump voters who had arrived to say they were very disappointed.
Before their invasion, which no-one but them had expected, Mr. Gatehouse spotted among them a bloke in fancy-dress and calling himself "The Qanon Shaman". Intrigued, he struck up a conversation with this man, but did not interview him. What he learnt led to him digging deeper, to try to understand Qanon and its origins, even originator.
We learnt its background went back over quite a number of years, even to a deeply unpleasant hoax about widespread paedophile rings. It festered in a mixture of febrile political slanging-matches by personal insults, the ghastly 'Pizzagate' myth ("The restaurant does not even have a basement", Gatehouse drily remarked), and obscure little web-sites accommodating mainly disaffected young men harbouring deep mysoginist, racist and generally nasty "~ist" views.
These sites included "8-Chan", owned by a father and son American duo based in the Phillipines; and "Qanon" as a user-name or conversation-title developed there. It might have stayed there, if a political-party campaigner had not found it and placed it on Facebook to use as an election-campaign weapon.
Subsequently it grew into something resembling a movement, or at least a kernel for hard-line social and political beliefs.
What Gabriel Gatehouse was unable to do, was discover Qanon's creator. I doubt we will ever know unless the individual owns up, whichis hardly likely. It struck me it might not even be by an individual, American national and resident, anyway.....