Trevor Perrin
The quiet co-designer of the Signal Protocol and sole author of the Noise framework that WireGuard is built on.
In 2013 Perrin and Moxie Marlinspike designed what was first called the Axolotl ratchet and later the Double Ratchet. Together with the X3DH key agreement and the XEdDSA signature scheme, both of which Perrin also specified, it became the Signal Protocol — now the encryption inside Signal, WhatsApp and several other messengers with billions of users between them.
In parallel he wrote the Noise Protocol Framework: a way to assemble handshakes from a small set of patterns instead of inventing a bespoke protocol every time. WireGuard, the Lightning Network and WhatsApp's transport layer all use it. Perrin rarely appears at conferences and prefers writing specifications to writing blog posts, which in cryptography is a virtue seldom rewarded with fame.