Albert Gonzalez
The Secret Service informant who was simultaneously running one of history's biggest card-number thefts – more than 100 million cards.
Albert Gonzalez was arrested in 2003 in connection with the carding forum ShadowCrew and became an informant for the Secret Service, which paid him to help take the forum down. On the side, he built an operation of his own. His crew got into retailer TJX through store Wi-Fi networks protected by the already broken WEP, and later into payment processor Heartland Payment Systems via SQL injection.
The 2008 Heartland breach exposed around 130 million card numbers. In 2010 Gonzalez was sentenced to 20 years in prison, at the time one of the longest US sentences for computer crime. The case helped tighten PCI DSS – and made agencies somewhat more careful about whom they put on the payroll.