The Morris Worm: On Nov. 2, 1988, Robert Tappan Morris released a worm that brought down one-tenth of the Internet -- which back then meant he crippled more than 6,000 computer systems. Named the Morris Worm, this exploit inspired the founding of a governmental anticyber-terrorism team, CERT (Computer Emergency Response Team), to deal with future Morris worms. Morris made the mistake of chatting about his worm for months before he actually released it on the Internet, so it didn't take long for the police to track him down.
Morris was one of the first to be tried and convicted under the Computer Fraud and Abuse Act, but he only had to perform community service and pay a fine, since the argument was made that the worm didn't destroy the contents of affected computers.
Morris said it was just a stunt, and added that he truly regretted wreaking $15 million worth of damage. That's what it cost to de-worm the machines his critter had penetrated. Morris's father, Robert Morris Sr., was at the time a computer security expert with the National Security Agency.