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.
In 1988, Robert T. Morris, a graduate student at Cornell, unleashed the first widely known computer "worm" -- a virus that spread over the Internet.
Morris said the whole thing was a benign experiment that got out of control, but prosecutors said he had caused hundreds -- if not tens of thousands -- of dollars in lost productivity for each computer affected. He was sentenced to three years' probation, community service, and a fine of $10,000 plus legal costs.
But like many of his ne'er-do-well brethren, he was a bright guy. In 1995 he co-founded a startup company that made software for online stores. In 1998 the firm was bought out, for about $45 million, by another online startup called Yahoo.
Morris is now a professor in the Computer Science and Artificial Intelligence Laboratory at M.I.T.
Kevin Poulsen had good taste in cars. In 1990 a Los Angeles radio station (102.7 on the FM dial) promised a free Porsche to the 102nd caller of the day. He'd already hacked into their phone lines, and mysteriously became caller number 102.
The government was already after him. Having first been caught in his teens -- and rewarded, after punishment, with a computer-security job at a high-tech lab -- he broke into computers run by the FBI and the Defense Department.
After 17 months on the run, he was arrested in 1991 and held without bail. The sentence he finally served -- 51 months -- was the longest for computer crimes at the time.
He does not run a computer security firm. Instead, he writes about it. His blog at Wired News is called "Threat Level."
Shawn Fanning, by most people's definition, is hardly a hacker, but he did more to change the way computers are used than most hackers, for good or evil, can ever hope.
Does his name ring a bell? Perhaps you'll remember his nickname: Napster. Friends at college called him that because of his short, kinky hair; he went on to use it as the name of a Web site for sharing his favorite music with friends.
Napster soon had a lot of friends -- a lot -- and music has never been the same since. People found that music, saved digitally in the MP3 format, sounded just about as good as the music recorded on Compact Discs -- and even better if the CD cost $15 while the MP3 download was free.
Record companies sued Napster. They sued college students who downloaded music from Napster. They won the battle, but lost the war.