Theo de Raadt

Born in South Africa in 1968 and raised in Canada, de Raadt co-founded NetBSD in 1993 and was pushed out of its core team after a falling-out that was largely about tone. His answer was a fork: OpenBSD, October 1995, with security as the stated priority and a line-by-line audit of the whole source tree.

The project went on to produce OpenSSH in 1999 — now the SSH implementation practically everyone runs — and LibreSSL in 2014, a scorched-earth cleanup of OpenSSL after Heartbleed. His mailing-list manner is famously blunt to the point of rudeness, but the slogan about only two remote holes in the default install, in a heck of a long time, has held up.