Latanya Sweeney

In 1997 Massachusetts released health data on state employees with the names stripped out. Sweeney, then an MIT graduate student, bought the Cambridge voter roll for twenty dollars, joined it on ZIP code, birth date and sex, and mailed Governor William Weld's records to his office. She went on to show that those three fields alone uniquely identify about 87 percent of the US population.

Her answer was k-anonymity (2002): every record should be indistinguishable from at least k−1 others. The model has known weaknesses, and Cynthia Dwork's differential privacy went further, but Sweeney's experiment still shapes how regulators — including those behind GDPR — treat pseudonymised data. She served as chief technologist at the FTC in 2014.