Pierre de Fermat
Fermat, Pierre de (1601–65), French mathematician, founder of modern number and probability theories. Fermat's Last Theorem, which was not proven until 1993, states that there is no whole number solution of xn+yn=zn, where x, y, and z are nonzero integers and n is an integer greater than 2. Fermat's Principle states that light (or other waves) will follow the path with the shortest travel time between 2 points.
See also: Mathematics.