William Penn Nixon, Sr., (1832 – February 20, 1912) was an American publisher and politician from Indiana. Following an extensive private education, Nixon graduated from the University of Pennsylvania and became involved in Ohio politics. He served one partial and one full term in the Ohio House of Representatives, then retired from elected politics. He founded a newspaper in Cincinnati, then sold his share to move to Chicago, Illinois. There, he became manager of the nascent Chicago Inter Ocean. He assumed the presidency of the company in 1876, holding it until his death. Nixon also served as president of the Associated Press and Collector of the Port of Chicago.