British-born mathematician who was awarded the Fields Medal in 1974 for his work in algebraic geometry.

Mumford attended Harvard University, Cambridge, Massachusetts, U.S. (B.A., 1957; Ph.D., 1961), staying on to join the faculty upon graduation. He served as vice president (1991–94) and president (1995–98) of the International Mathematical Union. Mumford was awarded the Fields Medal at the International Congress of Mathematicians in Vancouver, British Columbia, Canada, in 1974. As with a number of Fields Medalists, Mumford's prizewinning work was in algebraic geometry. In some of his early work Mumford took up David Hilbert (Hilbert, David)'s theory of invariants and applied it to new geometric problems couched in Alexandre Grothendieck (Grothendieck, Alexandre)'s theory of schemes. He continued the efforts of Oscar Zariski in making both algebraic and rigorous the work of the Italian school of algebraic geometers on the subject of algebraic surfaces. He was influential in bringing Grothendieck's ideas to the United States, where they prospered. He also contributed to the development of an algebraic theory of theta functions. In the 1980s Mumford moved to Brown University, Providence, Rhode Island, and began researching the mathematics of computer vision.

Mumford's publications include Geometric Invariant Theory (1965) and Algebraic Geometry (1976).