Arthur Hiram Day (February 1, 1890 – January 11, 1967) was an American lawyer, politician, judge, and college football coach. A Republican, served two terms as an Ohio State Senator in the 1920s and a six-year term as a justice of the Ohio Supreme Court, from 1935 to 1940. Day was the head football coach at Trinity University in Waxahachie, Texas for one season, in 1912.