Richard Charles "Dick" Lewontin (born March 29, 1929) is an American evolutionary biologist, geneticist, academic and social commentator. A leader in developing the mathematical basis of population genetics and evolutionary theory, he pioneered the application of techniques from molecular biology, such as gel electrophoresis, to questions of genetic variation and evolution.

In a pair of 1966 papers co-authored with J.L. Hubby in the journal Genetics,Lewontin helped set the stage for the modern field of molecular evolution. In 1979 he and Stephen Jay Gould introduced the term "spandrel" into evolutionary theory. From 1973 to 1998, he held an endowed chair in zoology and biology at Harvard University, and since 2003 has been a research professor there. He won the Crafoord Prize in 2015 for their pioneering analyses and fundamental contributions to the understanding of genetic polymorphism.