Donald Ervin Knuth (/kəˈnuːθ/ kə-NOOTH; born January 10, 1938) is an American computer scientist and mathematician. He is a professor emeritus at Stanford University. He is the 1974 recipient of the ACM Turing Award, informally considered the Nobel Prize of computer science. Knuth has been called the "father of the analysis of algorithms".

Knuth is the author of the multi-volume work The Art of Computer Programming. He contributed to the development of the rigorous analysis of the computational complexity of algorithms and systematized formal mathematical techniques for it. In the process, he also popularized the asymptotic notation. In addition to fundamental contributions in several branches of theoretical computer science, Knuth is the creator of the TeX computer typesetting system, the related METAFONT font definition language and rendering system, and the Computer Modern family of typefaces.

As a writer and scholar, Knuth created the WEB and CWEB computer programming systems designed to encourage and facilitate literate programming, and designed the MIX/MMIX instruction set architectures. He strongly opposes the granting of software patents, and has expressed his opinion to the United States Patent and Trademark Office and European Patent Organisation.

Donald Knuth was born in Milwaukee, Wisconsin, to Ervin Henry Knuth and Louise Marie Bohning. He describes his heritage as "Midwestern Lutheran German". His father owned a small printing business and taught bookkeeping. While a student at Milwaukee Lutheran High School, Knuth thought of ingenious ways to solve problems. For example, in eighth grade, he entered a contest to find the number of words that the letters in "Ziegler Giant Bar" could be rearranged to create; the judges had identified 2,500 such words. With time gained away from school due to a fake stomachache, Knuth used an unabridged dictionary and determined whether each dictionary entry could be formed using the letters in the phrase. He identified over 4,500 words, winning the contest. As prizes, the school received a new television and enough candy bars for all of his schoolmates to eat.

Knuth received a scholarship in physics to the Case Institute of Technology (now part of Case Western Reserve University) in Cleveland, Ohio, enrolling in 1956. He also joined the Beta Nu Chapter of the Theta Chi fraternity. While studying physics at Case, Knuth was introduced to the IBM 650, an early commercial computer. After reading the computer's manual, Knuth decided to rewrite the assembly and compiler code for the machine used in his school because he believed he could do it better.

In 1958, Knuth created a program to help his school's basketball team win its games. He assigned "values" to players in order to gauge their probability of scoring points, a novel approach that Newsweek and CBS Evening News later reported on.

Knuth was one of the founding editors of the Case Institute's Engineering and Science Review, which won a national award as best technical magazine in 1959. He then switched from physics to mathematics, and received two degrees from Case in 1960: his Bachelor of Science, and simultaneously a master of science by a special award of the faculty, who considered his work exceptionally outstanding.

At the end of his senior year at Case in 1960, Knuth proposed to Burroughs Corporation to write an ALGOL compiler for the B205 for $5,500. The proposal was accepted and he worked on the ALGOL compiler between graduating from Case and going to Caltech.