Erwin Arthur Renfer (December 11, 1891 – October 26, 1957) was an American baseball pitcher from 1910 to 1915. He compiled a 61–35 record in 131 minor league games, and he also appeared in one game in Major League Baseball for the Detroit Tigers in September 1913. Renfer spent most of the 1912 and 1913 seasons playing for the Ottawa Senators in the Canadian League. He appeared in 52 games for Ottawa, compiling a 34–10 record in 1912 and 1913. He also appeared in six Central League games for the during the 1912 season.