Joseph B. O'Hagan SJ (August 15, 1826 – December 15, 1878) was an Irish-American Catholic priest and Jesuit who was the president of the College of the Holy Cross from 1873 to 1878. Born in Ireland, he emigrated to Nova Scotia, Canada, at a young age and entered the seminary. While in Boston, Massachusetts, he decided to enter the Society of Jesus. He studied at Georgetown University and the Catholic University of Louvain before returning to the United States and becoming a chaplain in the Union Army during the Civil War.