Maby Albert Einstein. Since I feel his relativity theory brought us much further in science and philosophical dimension.

From the living I really like Neil deGrasse Tyson. I feel he does much for science in that he is vocal about how science works in words that are easy to digest. I actually do not know if what he studied also brought up some important breakthrought. But I think it is important to have scientists, that are able to communicate for a general audience and explain.

And last but no least Nikola Tesla, since he put down the basic work, on which the world began to electrificate.