Willy Albert Flegel is a German-American medical researcher, geneticist, and physician who is best known for his work in the field of the Rh blood group.

[1] Flegel is the chief of the laboratory services section of the Department of Transfusion Medicine at the National Institutes of Health Clinical Center (NIH).

He trained as specialist for transfusion medicine at the Universität Ulm, Germany and in molecular biology research at the University of California, San Diego.

Clinical appointments included: chief, Department of Immunohematology at the German Red Cross Blood Service Baden-Württemberg - Hessen in Ulm for 16 years.

[9] This work in collaboration with Franz F. Wagner refuted a scientific opinion that had been taught for decades.