Anthony Fauci is an American physician and immunologist who led the National Institute of Allergy and Infectious Diseases (NIAID) for nearly four decades, from 1984 to 2022. He played a key role in U.S. responses to major health crises, including HIV/AIDS, Ebola, and COVID-19, serving as a chief medical advisor to multiple presidents. Fauci is widely recognized for his contributions to infectious disease research and public health policy.