Edward Snowden
termprivacysecurity
The NSA contractor who in 2013 handed journalists a large archive of documents on US and allied signals-intelligence programmes, then left for Hong Kong and eventually Russia, where he remains beyond the reach of American prosecution.
For this field the significance is technical rather than political: the documents turned longstanding suspicions about bulk collection, tapped inter-datacentre links and weakened cryptographic standards into sourced fact. The industry response was immediate and durable - encryption between datacentres, HTTPS as a default rather than a feature, certificate transparency, and free certificates at scale. The disclosure itself was filmed in the Hong Kong hotel room and released as Citizenfour, which doubles as a record of operational security practised under real threat.
Also known as: nsa disclosures, 2013 leaks, citizenfour