In computer slang, J. Random Hacker is an arbitrary programmer (hacker).
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. may originally have been inspired by 'J. 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. Presper Eckert' (one of the co-inventors of the electronic computer)".
— "A Portrait of J. Random Hacker", the Jargon File[1]
"J. Random Hacker" is a popular placeholder name in a number of books and articles in programming.[2][3] J. Random Hacker even authored a book about ease of malicious hacking, Adventures of a Wi-Fi Pirate.[4] Also, J. Random Hacker was a main developer of I2P software.
Over time, J. Random X has become a popular cliché or snowclone in computer lore, with more types of "random" (meaning "arbitrary") categories of people, such as "J. Random Newbie",[5] J. Random User,[6] or J. Random Luser.