Har Gobind Khorana (9 January 1922 – 9 November 2011) was an Indian-American biochemist. While on the faculty of the University of Wisconsin–Madison, he shared the 1968 Nobel Prize for Physiology or Medicine with Marshall W. Nirenberg and Robert W. Holley for research that showed the order of nucleotides in nucleic acids, which carry the genetic code of the cell and control the cell's synthesis of proteins. Khorana and Nirenberg were also awarded the Louisa Gross Horwitz Prize from Columbia University in the same year.

Born in British India, Khorana served on the faculties of three universities in North America. He became a naturalized citizen of the United States in 1966, and received the National Medal of Science in 1987.

Har Gobind Khorana was born to Ganpatrai Khorana and Krishna Devi, in Raipur, a village in Multan, Punjab, British India, in a Punjabi Hindu Khatri family. The exact date of his birth is not certain but he believed that it might have been 9 January 1922; this date was later shown in some documents, and has been widely accepted. He was the youngest of five children. His father was a patwari, a village agricultural taxation clerk in the British Indian government. In his autobiography, Khorana wrote this summary: "Although poor, my father was dedicated to educating his children and we were practically the only literate family in the village inhabited by about 100 people." The first four years of his education were provided under a tree, a spot that was, in effect, the only school in the village. He did not even own a pencil until age 6.

He attended D.A.V. (Dayanand Anglo-Vedic) High School in Multan and Government College, in Lahore. Later, he studied at the Punjab University in Lahore, with the assistance of scholarships, where he obtained a bachelor's degree in 1943 and a Master of Science degree in 1945.

Khorana lived in British India until 1945, when he moved to England to study organic chemistry at the University of Liverpool on a Government of India Fellowship. He received his PhD in 1948 advised by Roger J. S. Beer. The following year, he pursued postdoctoral studies with Professor Vladimir Prelog at ETH Zurich in Switzerland. He worked for nearly a year on alkaloid chemistry in an unpaid position.

His family moved to Delhi from Multan as refugees during the partition of India and Khorana was never to visit his place of birth after that. During a brief period in 1949, he was unable to find a job in Delhi. He returned to England on a fellowship to work with George Wallace Kenner and Alexander R. Todd on peptides and nucleotides. He stayed in Cambridge from 1950 until 1952.

He moved to Vancouver, British Columbia, with his family in 1952 after accepting a position with the British Columbia Research Council at University of British Columbia. Khorana was excited by the prospect of starting his own lab, a colleague later recalled. His mentor later said that the council had few facilities at the time but gave the researcher "all the freedom in the world". His work in British Columbia was on "nucleic acids and synthesis of many important biomolecules" according to the American Chemical Society.

In 1960 Khorana accepted a position as co-director of the University of Wisconsin–Madison's Institute for Enzyme Research He became a professor of biochemistry in 1962 and was named Conrad A. Elvehjem Professor of Life Sciences in 1964. While at Wisconsin, "he helped decipher the mechanisms by which RNA codes for the synthesis of proteins" and "began to work on synthesizing functional genes". During his tenure at this university, he completed the work that led to sharing the Nobel Prize in 1968. The Nobel web site states that it was "for their interpretation of the genetic code and its function in protein synthesis". Har Gobind Khorana's role is stated as follows: he "made important contributions to this field by building different RNA chains with the help of enzymes. Using these enzymes, he was able to produce proteins. The amino acid sequences of these proteins then solved the rest of the puzzle."