Eugene Wilder Chafin (November 1, 1852 – November 30, 1920) was an United States politician from the Prohibition Party. Chafin was born in East Troy, Wisconsin and worked as a lawyer in Waukesha, Wisconsin from 1876 to 1900. He was the Prohibition Party candidate for Congress (Wisconsin) in 1882 and (Chicago) in 1902, for Attorney-General of Wisconsin in 1886 and 1900, for Governor of Wisconsin in 1898, and for Attorney-General of Illinois in 1904. In 1908 he was appointed to the bar of the Supreme Court of the United States and in the following year moved to Arizona. While in Arizona he ran for that state's United States Senate Seat.