Anna Kournikova (2001)

The Anna Kournikova virus is so named because it tricked its recipients into thinking they were downloading a sexy picture of the tennis star. Financial damages associated with Kournikova were limited, but the virus had a big pop culture impact: It became a plot point in a 2002 episode of the sitcom Friends.

Sasser (2004)

In April 2004, Microsoft issued a patch for a vulnerability in Windows’ Local Security Authority Subsystem Service (LSASS). Shortly after, a teenager in Germany released the Sasser worm to exploit the vulnerability in unpatched machines. Multiple variants of Sasser took out airline, public transportation, and hospital networks, causing $18 billion in damage.