Top 5 Famous Computer Hackers: From Conficker to the First Computer Virus

Top of the List: America's Best-Known Hackers

So here are some of the most famous -- or infamous -- hackers, compiled with the help of Symantec, the Justice Department, the National White Collar Crime Center, and several technology consultants. You may despise some of them; others, you may actually like. Please feel free to suggest others, or argue with our choices, in our comments section.

Fred Cohen

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In 1983, Fred Cohen, then a Ph.D. student at the University of Southern California, wrote a short program, as an experiment, that could "infect" computers, make copies of itself, and spread from one machine to another. It was benign. It was hidden inside a larger, legitimate program, which was loaded into a computer on a floppy disk -- something few computers sold today can accommodate anymore.

Other computer scientists had warned that computer viruses were possible, but Cohen's was the first to be documented. A professor of his suggested the name "virus." Cohen now runs a computer security firm.

"You could write defenses 'til the cows come home," he told ABC News back in 1988, "and it's guaranteed that eventually that some virus will be able to get past those defenses."

Kevin Mitnick

It takes some diligence to get the Justice Department to call you "the most wanted computer criminal in United States history." Kevin Mitnick was diligent.

He was first arrested when he was 17, and spent time in and out of jail. He broke into computer systems at Novell, Motorola, Sun, Fujitsu and other firms, stealing their software and crashing their machines. He was caught, for the last time, in 1995.

He did time -- four years of it -- before he was convicted and sentenced to 46 months in prison with credit for time already served.

When he was released, and finished a period when he was under orders to stay away from computers, he wrote two books -- with hacker-ish titles like "The Art of Intrusion." (If you ever saw a movie called "Takedown," it's about Mitnick.) He now runs a computer security firm.