Bernard Fisher (August 23, 1918 – October 16, 2019) was an American surgeon and a pioneer in the biology and treatment of breast cancer. He was a native of Pittsburgh. He was Chairman of the National Surgical Adjuvant Breast Project at the University of Pittsburgh School of Medicine. His work established definitively that early-stage breast cancer could be more effectively treated by lumpectomy, in combination with radiation therapy, chemotherapy, and/or hormonal therapy, than by radical mastectomy.