While it sounds cliche, John Carmack, along with Michael Abrash, are among several people that begat my interest in programming (with a focus towards games of course ;D), at a time when I was still unsure of what I wanted to do in my life.

It's interesting to see the evolution of what was happening at the time in the game development industry, and then correlate that to what I was experiencing at the time as I was growing up, and playing these games.