William Clouser Boyd (March 4, 1903 - February 19, 1983) was an American immunochemist, who with his wife Lyle, during the 1930s, made a worldwide survey of the distribution of blood types. He discovered that blood groups are inherited and not influenced by environment. By genetic analysis of blood groups he hypothesised that human races are populations that differ by alleles. On that basis, he divided the world population into 13 geographically distinct races with different blood group gene profiles. Boyd co-wrote the book Races and People with Isaac Asimov.

Later, Boyd discovered lectins in plants. He also studied the blood groups of mummies.

Selected Bibliography

• Races and People, by Isaac Asimov and William C Boyd, 1958.

• Genetics and the races of man: An introduction to modern physical anthropology, William C Boyd, 1950.