Michael Hayden
The Air Force general who ran both the NSA and the CIA and gave the metadata debate its most quoted line.
Hayden directed the NSA from 1999 to 2005 and the CIA from 2006 to 2009. After 11 September 2001 the NSA under his leadership intercepted and collected communications without warrants under the Stellar Wind programme, revealed by the New York Times in 2005 and later partly written into law. He also inherited an agency that had fallen behind the internet technically and pushed it from listening to radio towards tapping fibre.
In a 2014 debate he agreed with his opponent that metadata reveals more or less everything about a person, and added: "We kill people based on metadata." It was meant to illustrate how useful the data is; it has been quoted ever since as the clearest proof that metadata is anything but harmless.