Date reported: 06/01/84
How it happened: A stolen computer password
Despite happening over 30 years ago the TWR breach remains on the all time biggest data bungles in history.
TRW Information Systems was an American corporation that was involved in a variety of businesses, including aerospace, automotive, and credit reporting until it was acquired by Northrop Grumman in 2002.
In 1984 retro-hackers managed to use a stolen computer password to access the firm's systems and compromise the credit histories of over 90 million people.
You can read TWR's original explanation of the hack here.