If I owe the start of my career to Apple, it's only fair to admit that I owe the bulk of it to Dennis Ritchie. Dennis Ritchie was a co-creator of unix, the inventor of the C Programming Language, and the co-author of this gem:
I'm long past needing this book, but I keep it on my shelf. Both as a reminder of where I came from, and as a monument to the absolute zenith of technical writing.
There's not a computer system in the world today that doesn't owe some of its heritage to either C or Unix. Dennis was a quiet giant of computer science. He wasn't a public figure like Steve Jobs, but his impact on the field of technology was at least as large, and his loss an equally terrible blow.