Richard D. Alexander (November 18, 1929 – August 20, 2018) was an American zoologist who was a professor at the University of Michigan and curator at the university's museum of zoology of in Ann Arbor, Michigan. His scientific pursuits integrated the fields of systematics, ecology, evolution, natural history and behaviour. The salient organisms in his research are wide-ranging, from the orthopterans (grasshoppers, katydids and crickets) and cicadidae (cicadas) to vertebrates: dogs, horses, and primates, including humans.