You can now see profiles of famous scientists on Google Scholar citations. Here are links to a few of them (via Ben L.). Von Neumann, Einstein, Newton, Feynman But their impact on science pales in comparison (with the possible exception of Newton) to the impact of one statistician: R.A. Fisher. Many of the concepts he developed are so common and are considered so standard, that he is never cited/credited. Here are some examples of things he invented along with a conservative number of citations they would have received calculated via Google Scholar*.
This post written by Jeff Leek and Rafa Irizarry. The p-value is the most widely-known statistic. P-values are reported in a large majority of scientific publications that measure and report data. R.A. Fisher is widely credited with inventing the p-value. If he was cited every time a p-value was reported his paper would have, at the very least, 3 million citations* - making it the most highly cited paper of all time.