Stephen Ira Katz (1941 – December 20, 2018) was an American immunodermatologist who served as the director of the National Institute of Arthritis and Musculoskeletal and Skin Diseases from 1995 to 2018.

He was the Marion B. Sulzberger Professor of Dermatology at the Uniformed Services University of the Health Sciences from 1989 to 1995.

From 1972 to 1974, Katz did a postdoctoral fellowship at the Royal College of Surgeons of England and obtained a Ph.D. in immunology from the University of London in 1974.

[1] Katz then became senior investigator in the dermatology branch of the National Cancer Institute (1974–2014) and assumed the position of acting chief in 1977.

His research demonstrated that skin is an important component of the immune system both in its normal function and as a target in immunologically-mediated disease.

In addition to studying Langerhans cells and epidermally-derived cytokines, Katz and his colleagues investigated inherited and acquired blistering skin diseases.