William Rowan Hamilton, Irish physicist, astronomer, and mathematician (died 1865)

Sir William Rowan Hamilton was an Irish mathematician, physicist, and astronomer who made numerous major contributions to abstract algebra, classical mechanics, and optics. His theoretical works and mathematical equations are considered fundamental to modern theoretical physics, particularly his reformulation of Lagrangian mechanics. His career included the analysis of geometrical optics, Fourier analysis, and quaternions, the last of which made him one of the founders of modern linear algebra.