Henry Darger - Reclusive janitor revealed posthumously to be the author of a 15,145-page fantasy manuscript depicting young children being tortured and massacred
Some of his work is unbelievably impressive, like a 30 foot wide, double sided painting. He has had no training as an artist or in writing (as far as I can see).
This guy is one of the most celebrated outsider artists, and there is also a lawsuit in progress from some of his wayyyy distant relatives trying to rob all his trademarks and copyrights he left to his friends.
Oh okay some schizo in a cave writes a manuscript about child torture and massacres and 4 billion people worship him but you do it in the 20th century and suddenly now there’s a problem