Gruber invented Markdown, full stop. He may have selected the particular syntactic conventions it uses, but the idea of parsing ASCII markup and converting it

Gruber invented Markdown, full stop. He may have selected the particular syntactic conventions it uses, but the idea of parsing ASCII markup and converting it to a formatter's input syntax is much older. I'm aware of prior art dating back to 1986 or so -- and wouldn't be surprised if that wasn't the first either.