In computer slang, J. Random Hacker is an arbitrary programmer

Programmer

A programmer, computer programmer or coder is someone who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to...

 (hacker).
"J. Random Hacker" is a popular placeholder name

Placeholder name

Placeholder names are words that can refer to objects or people whose names are either temporarily forgotten, irrelevant, or unknown in the context in which they are being discussed...

 in a number of books and articles in programming. J. Random Hacker even authored a book about ease of malicious hacking, Adventures of a Wi-Fi Pirate. Also, J. Random Hacker was a main developer of I2P

I2P

I2P is a mixed-license, free and open source project building an anonymous network .The network is a simple layer that applications can use to anonymously and securely send...

 software.

Over time, J. Random X has become a popular cliché

Cliché

A cliché or cliche is an expression, idea, or element of an artistic work which has been overused to the point of losing its original meaning or effect, especially when at some earlier time it was considered meaningful or novel. In phraseology, the term has taken on a more technical meaning,...

, a snowclone

Snowclone

A snowclone is a type of cliché and phrasal template originally defined as "a multi-use, customizable, instantly recognizable, time-worn, quoted or misquoted phrase or sentence that can be used in an entirely open array of different variants"....

, in computer lore, with more types of "random" (meaning "arbitrary") categories of people, such as "J. Random Newbie

Newbie

Newbie or noob is a slang term for a novice or newcomer, or somebody inexperienced in any profession or activity. Contemporary use can particularly refer to a beginner or new user of computers, often concerning Internet activity, such as online gaming or Linux use...

", J. Random User, or J. Random Luser

Luser

In Internet slang, a luser is a painfully annoying, stupid, or irritating computer user.It is a portmanteau of "loser" and "user"....

.