Maurice Ralph Hilleman (August 30, 1919 – April 11, 2005) was an American microbiologist who specialized in vaccinology and developed over 40 vaccines, an unparalleled record of productivity. Of the 14 vaccines routinely recommended in current vaccine schedules, he developed eight: those for measles, mumps, hepatitis A, hepatitis B, chickenpox, meningitis, pneumonia and Haemophilus influenzae bacteria.