Michael Stuart Gottlieb is an American physician and immunologist known for his 1981 identification of acquired immune deficiency syndrome (AIDS) as a new disease. Gottlieb was born in 1947 in New Jersey and was educated at Rutgers University, the University of Rochester, and Stanford University, where had a fellowship in immunology. In 1980, he accepted a position at the UCLA School of Medicine, where he worked for nearly 20 years. In 2019, he accepted a position at APLA Health in Los Angeles, a nonprofit devoted to the health and well-being of people living with HIV/AIDS.

Gottlieb is also well-known as the personal physician to actor Rock Hudson after Hudson's AIDS diagnosis. He also established, with a gift from the Hudson estate and with the help of Hudson's friend Elizabeth Taylor and medical researcher Mathilde Krim, the American Foundation for AIDS Research. Gottlieb was also actively involved in fundraising and philanthropy related to AIDS treatment and advocacy.

He was also an investigator in early clinical trials of several different AIDS drug treatment studies, including AZT, an antiretroviral which was later approved by the FDA for the treatment of HIV/AIDS.