Programmer at IdSoftware, responsible for Wolfenstein, Doom and Quakes 1, 2 and QuakeThreeArena. Considered one of the best Graphics programmers alive (vying with MichaelAbrash for the title). Also one of the brains behind ArmadilloAerospace? (http://www.armadilloaerospace.com).
Interesting footnotes in the JohnCarmack history is that he started Quake (and reportedly finished Doom) on NeXt operating systems. I'd imagine that he was working on PaRisc rather than the original NeXt hardware, since a few years ago they advertised they were giving away PaRisc machines running NextStep.
A quote from his .plan (6/27/99):
I got tired of thinking about it, and just started coding in some infrastructure to do extra lighting passes. I just made a gradient circle texture for the lighting, and generated the texture coordinates by just translating and scaling X and Y from the world coordinates.
I got it running, grabbed a rocket launcher, and fired down a hallway. It looked just fine. I was stunned. I had been thinking about complex ramifications of weird edge cases for the past year when all it took was a couple hours of programming and the simplest possible approach to make it work decent. Sigh. :-)