Theo de Raadt is one of the key hackers outside the mainstream GNU/Linux world. Here's his self-penned bio:
I am the founder of OpenBSD -- a freely redistributable 4.4BSD-based operating system with an emphasis on security. Donations allow me to put my efforts into OpenBSD and related projects. In 1999, I created OpenSSH with other members of OpenBSD. It is now incorporated into all Unix systems plus hundreds of other network enabled products. It is now the most "vendor re-used" piece of open source software, with more than 90% of the SSH market.
On Open Enterprise blog.