A mythical figure like the Unknown Soldier; the archetypal hacker nerd.
This term is one of the oldest in the hacker's jargon, apparently going back to MIT in the 1960s.
Fred Muggs', a show-biz chimpanzee whose name was a household word back in the early days of TMRC, and was probably influenced by 'J.
Random Hacker" is a popular placeholder name in a number of books and articles in programming.
Random Hacker even authored a book about ease of malicious hacking, Adventures of a Wi-Fi Pirate.