Alexander Robertus Todd, Baron Todd (October 2, 1907 - January 10, 1997) was a British biochemist whose research on the structure and synthesis of nucleotides, nucleosides, and nucleotide coenzymes gained him the Nobel Prize for Chemistry. After graduating from the University of Oxford, he held posts with the Lister Institute, the University of Edinburgh, and the University of London, where he was appointed Reader in Biochemistry. Todd became the Sir Samuel Hall Chair of Chemistry and Director of the Chemical Laboratories of the University of Manchester in 1938, where he began working on nucleosides, compounds that form the structural units of nucleic acids (DNA and RNA). In 1949, he synthesized adenosine triphosphate (ATP) and flavin adenine dinucleotide (FAD). Among his many honours, including over 40 honorary degrees, he was elected as a Fellow of the Royal Society in 1942, was President of the Royal Society from 1975 to 1980 and became a member of the Order of Merit in 1977. He died in 1997, at the age of 89, after a heart attack.