Ignatius Michael Duffy (January 27, 1875 – October 6, 1958) was an American college football coach.
A native of Ann Arbor, Michigan, Duffy attended Ann Arbor High School.
In 1895, while a student at Michigan, Duffy served as the head football coach for Alma College in Alma, Michigan.
[4] In 1897, he served as an assistant coach for the Michigan football team.
[5] Duffy was a member of the Alpha Epsilon fraternity.