Mark Zbikowski — In his senior year at Roeper, c. 1973/4, Zbikowski became known as one of the earliest computer crackers, after cracking the security system on Wayne State University's MTS (Michigan Terminal System, developed at University of Michigan) mainframe for his own amusement. According to Zbikowski, when he offered to show the university how to fix the security leak, university officials threatened prosecution and offered him a job during the same meeting.
Jonathan James (also known as c0mrade) made unauthorized copies of software controlling the International Space Station's life sustaining elements, and intercepted thousands of electronic messages relating to U.S. nuclear activities from the Department of Defense. Sentenced at age 16, he was the youngest cybercriminal ever incarcerated in the United States.
Dark Avenger — (but not
The Dark Avenger

) Bulgarian virus writer that popularized polymorphic code in 1992 as a means to circumvent the type of pattern recognition used by Anti-virus software, and nowadays also intrusion detection systems.
Markus Hess — A West German, he hacked into United States Military sites and collected information for the KGB; he was eventually tracked down by Clifford Stoll.
Vladimir Levin — This mathematician allegedly masterminded the Russian hacker gang that tricked Citibank's computers into giving out $10 million. To this day, the method used is unknown, but can be speculated.
Robert Tappan Morris — In 1988 while a Cornell University graduate student was the writer of the first worm, Morris Worm, which used buffer overflows to propagate.
Nahshon Even-Chaim (also known as Phoenix) — Leading member of Australian hacking group The Realm. Targeted US defense and nuclear research computer systems in late 1980s until his capture by Australian Federal Police in 1990. He and fellow Realm members Electron and Nom were the world's first computer intruders prosecuted based on evidence gathered from remote computer intercept.
Kevin Poulsen — In 1990 Poulsen took over all telephone lines going into Los Angeles area radio station KIIS-FM to win an automobile in a call-in contest. Poulsen went on to a career in journalism, including several years as editorial director at SecurityFocus.
Kevin Mitnick - Mitnick was convicted in the late 1990s of illegally gaining access to computer networks and stealing intellectual property.
Jon Murdock (also known as Xtasy) — In 2004, Murdock was convicted on multiple counts of cyber-terrorism, internet fraud, and was then prosecuted for allegedly causing over $12,000,000 in online theft from thousands of stolen paypal and e-gold accounts. After Murdock's release in 2006 at the age of 19, Murdock was then indicted on another 17 counts of high-tech fraud and was linked to numerous underground "cracking communities" and forums. Murdock will be released from prison in 2008, following a 5 year probationary period.
David L. Smith — In 1999 Smith launched the Melissa Worm, causing $80 million dollars worth of damage to businesses. Originally sentenced to 40 years, he eventually served only 20 months when he agreed to work undercover for the FBI.
Celestino Canto- Creator of the celey Trojan & online theft from thousands of stolen paypal and e-gold accounts.