Also, while Turing made very important contributions to the fundamentals of computer science, there were others who were working on similar models of computability, such as Alonzo Church. I have great admiration for Turing (especially after having read his biography by Hodges[1]), but I think that if Turing had never come along, we'd still have computers and computer science today.
Turing's most influential work may have been his wartime cryptanalysis, which may have been pivotal in the Allies' victory in WWII. On the other hand, Einstein (and others) urged President Roosevelt to develop nuclear weapons before the Germans did, which certainly influenced today's world in significant ways.
How about Claude Shannon? He has the right to be called as influential as Turing within the information engineering world. Basically his work laid the foundation for making digital ALUs possible. Not to mention his enormous contributions to information theory.
How about Alan Kay, who invented (or discovered) object oriented programming?
How about John McCarthy who invented Lisp? And, moreover, the idea of macros. Many of the things we take for granted on modern platforms (for example, garbage collection) originated with Lisp, so the invention of Lisp laid a foundation for the evolution of programming languages.