William James Mayo (June 29, 1861 – July 28, 1939) was a physician and surgeon in the United States and one of the seven founders of the Mayo Clinic. He and his brother, Charles Horace Mayo, both joined their father's private medical practice in Rochester, Minnesota, USA, after graduating from medical school in the 1880s. In 1919, that practice became the not-for-profit Mayo Clinic.
