Robert Spitzer -- some people call him the Father of Modern Psychiatry.
In 1980 he took the DSM II, widely criticized for unreliability and lack of validity, and as editor of the DSM III, turned this obscure publication of the American Psychiatric Association into the standard reference work that defined every psychiatric disorder we've got. It was research-based. It listed objective criteria. It was honkin' big, but it could be understood, not only by researchers, but also by practitioners.
Spitzer's acolyte, Allen Frances edited the DSM IV, which added a lot of information, but did not change Spitzer's basic framework for how these diseases are characterized. Frances was a consultant for the DSM V, until he quit, basically because the new editors started to rethink things. Frances now leads the charge against the DSM V, which has delayed its publication. I won't develop that theme right now...
Robert Spitzer is the Man.
With Great Power Comes Great Responsibility