William Michael O'Neill (born May 6, 1947) is an American lawyer, judge and political figure. He was elected to the Ohio Supreme Court in 2012, for a term beginning January 2013. He served as an appellate judge on the Ohio Eleventh District Court of Appeals for 10 years. Twice, O'Neill was the Democratic nominee for U.S. Representative in Ohio's 14th congressional district. He announced on October 29, 2017, as a candidate for Ohio Governor in the 2018 election. On December 8, 2017, he announced he would resign from the Supreme Court on January 26, 2018.