(3) Blaise Pascal
If it's possible to be considered a genius and still be underrated, Pascal pulls off the trick. In the 17th century, Pascal made landmark contributions to religious philosophy (where he contended that God shouldn't be experienced through reason and logic), mathematics (where his development of Pascal's triangle laid the groundwork for the study of probability), engineering (he made one of the first mechanical calculators), and physics (where Pascal's law describes what happens to a liquid under pressure). Given all of these huge achievements, it's hard to believe he died at just 39.
(14) Robert Venturi
Other nominees killed off diseases or fended off military forces, but Venturi helped save us from an even more insidious threat: boring buildings. At a time when the bland, clean-lined functionalism of the International style was all the rage among architects, Venturi appeared as a voice in the wilderness advocating a more vibrant architecture that wasn't totally divorced from historical influence and also drew on kitschy influences. His texts like Complexity and Contradiction in Architecture and Learning From Las Vegas, a serious study of Vegas' heavily ornamented styles, helped shape architecture in the second half of the 20th century, and his eclectic designs explore just how playful and fun postmodernism can be.
Venturi's writings may have changed the way we look at architecture and struck a blow for anyone bored by boxy skyscrapers, but Pascal was the intellectual equivalent of a five-tool player. The Frenchman originally made his breakthrough studies in probability to answer questions related to gambling, and we're pretty sure he wouldn't bet against himself here.
[See the whole bracket here.]