Linus Torvalds – The Linux kernel author
Dave Thomas – Author of the „Pragmmatic Programmer”, „Programming Ruby” and other great books about programming. One can read his mainly programming-related thoughts here.
Steve Yegge – Probably the least known from guys here, but also made one of the most interesting answers, has a popular weblog about programming. He is also the author of a game called „Wyvern”.
Peter Norvig – Research Director at Google, a well known Lisper, author of famous (in some circles at least) books about AI. See his homepage.
Guido Van Rossum – The Python language creator
James Gosling – The Java language creator
Tim Bray – One of the XML and Atom specifications author and a blogger too.
Interesting answers to the first question on how these programmers learnt programming shows that most of these learnt programming on their own thru books, playing with code etc and then some of these did enrol in a formal programming degree.
An answer from David Heinmeier Hansson, one of my favorite programmers and a great individual:
I learned programming by starting to put together my first web page in HTML. Then I wanted to make some dynamic pieces and picked up first ASP then PHP. After I already knew how to program, I then started on a joint computer science and business administration degree.