| John Duffy | |
| Fullname: | John J. Duffy |
| Birth Date: | 6 September 1905 |
| Death Place: | Woburn, Massachusetts, United States |
| Position: | Fullback |
| Years1: | 1925–1927 |
| Years2: | 1927–1929 |
| Years3: | 1929–1930 |
| Years4: | 1930 |
| Years5: | 1930 |
| Years6: | 1930 |
| Clubs6: | New York Soccer Club |
| Caps1: | 18 |
| Caps2: | 4 |
| Caps3: | 1 |
| Caps4: | 2 |
| Caps5: | 3 |
| Caps6: | 1 |
| Goals1: | 0 |
| Goals2: | 0 |
| Goals3: | 0 |
| Goals4: | 0 |
| Goals5: | 0 |
| Goals6: | 0 |
| Nationalyears1: | 1928 |
| Nationalteam1: | United States |
| Nationalcaps1: | 2 |
| Nationalgoals1: | 0 |
John Duffy (September 6, 1905 – September 27, 1984 in Woburn, Massachusetts) was a former U.S. soccer full back. Duffy played five years in the American Soccer League and earned two caps with the U.S. national team in 1928.[1]
In 1925, Duffy signed with the Philadelphia Field Club of the American Soccer League. He spent two seasons in Philadelphia before moving to the Newark Skeeters for the 1927–1928 season. In 1928, the Skeeters were suspended from the ASL and moved to the Eastern Professional Soccer League. In 1929, Duffy moved to the New York Nationals. In 1930, the Nationals were renamed the New York Giants. Duffy began the fall 1930 season with the Giants before playing three games with the Brooklyn Wanderers and finished the fall with one game with the New York Soccer Club.[2]
Duffy earned two caps with the U.S. national team. The first came at the 1928 Summer Olympics when the U.S. lost to Argentina 11–2. Following this loss, the U.S. tied Poland, 3-3, on June 10, 1928.[3]