Back in the Commander Keen days, Tom Hall created the id logo.
In 1992, Kevin Cloud updated the id logo. Tom and I were getting tired of the one we created back in the Keen days and before we released Wolfenstein 3D, Kevin fired up Adobe Illustrator on NeXTSTEP and created the id logo in a day.
Fast forward to Quake development in 1996, and while I was working with Sasha Shor on all the Quake packaging and marketing materials, I decided to change the id logo. The game we were making, Quake, was meant to be violent, disturbing and unsettling. It was supposed to, as much as we could, directly represent what the word "id" meant. Our clean, neat id logo didn't match the game or the package design that was shaping up.
I told Sasha,"I want you to fuck up the logo. Really mess it up as if something clawed at it, scratched at it, or it just got shot at several times." So, she did. And that logo has stood for the past 14 years.