UNIX

UNIX began with Ken Thompson who first thought of the idea of UNIX. Dennis Ritchie was the first collaborator. Ritchie created C, then he and Thompson used C to write UNIX. Both previously worked on Multics, reused some ideas from it. Douglas McIlroy introduced the idea of pipes, a major element of UNIX.

One programmer -- one -- wrote a system language.
Two programmers -- two -- wrote an operating-system.
And they did it right, the first time.
Those are phenomenal achievements.