Chad Orzel asks you to identify The Velvet Underground of Science by which he means an individual who isn't very famous but had a huge impact on science. Naturally, he has an example from physics.
I have an example from molecular biology. Max Delbrück (1906-1981) was one of the founders of the 'phage school (along with Salvador Luria). Delbrück began his science career as a physicist but when he went to the USA he switched to biology and soon became interested in bacteria and bacteriophage.1 During the 40s, 50s, and 60s he had a huge influence on the members of the 'phage group who used to meet regularly at Cold Spring Harbor where Delbrück taught a summer course in 'phage genetics.
Jim Watson, Matt Meselson, Franklin Stahl, Gunther Stent, Seymour Benzer, Edward Kellenberger, and Alfred Hershey are just a few of the scientists who were directly influenced by Delbrück. They all got together to contribute to Phage and the Origins of Molecular Biology in 1966. The book was a Festschrift in honor of Max Delbrück on his 60th birthday.
There were many more second and third generation scientists who grew up in the 'phage group. My own supervisor used to refer frequently to Delbrück's "Principle of Limited Sloppiness" as an effective way of doing science.
Delbrück, Alfred D. Hershey, and Luria won the Nobel Prize in 1969 but he (Delbrück) is still not very well known among today's students. I think that every biochemistry and molecular biology student should have to read The Eighth Day of Creation by Horace Freeland Judson in order to learn the history of their field.
They might discover that much of what they think of as "modern" was actually understood almost half a century ago.
Photo Credits: Top: Delbrück in the early 1940s from Wikipedia. Bottom: Delbrück and Luria at Cold Spring Harbor in 1953.
1. Physics was too easy—he wanted more of a challenge.