Irwin Mark Freedberg (born c. 1933, Brookline, Massachusetts; died July 17, 2005, New York City) was an American dermatologist. He taught dermatology at Harvard Medical School, was Director of the Department of Dermatology at Johns Hopkins University, was the first chief of dermatology at Beth Israel Hospital, and was the George Miller MacKee Professor and Chairman of the Ronald O. Perelman Department of Dermatology at the New York University Medical Center. He studied the protein keratin (the main component of hair, nails, and skin) and keratinocytes (the most common cells in the epidermis).