Ernest Beutler (September 30, 1928 – October 5, 2008) was a German-born American hematologist and biomedical scientist.
He made important discoveries about the causes of a number of diseases, including anemias, Gaucher disease, disorders of iron metabolism and Tay–Sachs disease.
He was also among the first scientists to identify X-inactivation as the genetic basis of tissue mosaicism in female mammals, and pioneered a number of medical treatments, including bone marrow transplantation techniques.
Beutler served as a Professor, then Chairman, of the Department of Molecular and Experimental Medicine at The Scripps Research Institute in La Jolla, California from 1979 until 2008.