John Spencer "Big Joe" Curtis (November 14, 1882 – January 29, 1972) was an American football player and coach. While playing for the University of Michigan, he was selected as a first-team All-Western tackle three consecutive years from 1904 to 1906 and as an All-American in 1904 and 1905. In his four seasons as the starting left tackle for the Michigan Wolverines, the team compiled a record of 37–2–1, won two national championships and outscored opponents by a combined total of 1,699 to 60. Curtis later served as the head football coach at Tulane University from 1907 to 1908 and at the Colorado School of Mines in 1909.