An email from someone on a related topic has reminded me of someone else you should make sure is only your list (not sure if you already have him): J. C. R. Licklider; we lost him on June 26, 1990. He didn't write much code himself, but the work of people he funded (e.g. Doug Engelbart, the ARPANet guys, Multics, etc, etc, etc) to work on his vision has led to today's computerized, information-rich world. For people who only know today's networked world, the change from what came before, and thus his impact on the world (since his ideas and the work of people he sponsored led, directly and indirectly, to much of it), is probably hard to truly fathom. He is, in my estimation, one of the most important and influential computer scientists of all. I wonder how many computer science people had more of an impact; the list is surely pretty short. Babbage; Turing; who else? Noel