William A. Blattner is an American virologist and physician known for his pioneering studies on the epidemiology of human retroviruses. He is a professor of medicine at the University of Maryland School of Medicine, where he co-founded the Institute of Human Virology (IHV) with Robert Gallo and Robert R. Redfield in 1996. He subsequently helped found the Institute of Human Virology, Nigeria, which has screened over 1 million Nigerians for HIV/AIDS. He retired from his position as associate director of the IHV and director of its Division of Epidemiology and Prevention on January 31, 2016. He is also the founding editor-in-chief of the Journal of Acquired Immune Deficiency Syndromes, and serves as its co-editor-in-chief along with Paul A. Volberding.