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.

He entered the Jesuit novitiate in December of that year, and studied rhetoric and philosophy at Saint John's College in Maryland.

[2] He was assigned to the Excelsior Brigade, under the command of Major General Daniel Sickles,[3] just after the unit arrived in Washington, D.C., in July 1861.

[4] While at first O'Hagan viewed the soldiers as lacking moral character, as some had joined the army as a condition of their release from prison on Blackwell's Island in New York City, his opinion of them changed by the end of his first year as chaplain.

[5] When the Excelsior Brigade became a part of Major General Joseph Hooker's command in the fall of 1861, O'Hagan was made chaplain to the 73rd New York Infantry Regiment.

[1] In the spring of 1878, O'Hagan's health began to decline and his physicians recommended that he recuperate by spending the winter months in the warm weather of San Francisco, California.

[8] At the request of the Maryland provincial superior, his body was eventually disinterred in 1879 and taken to San Francisco and then overland to Worcester, Massachusetts,[13] where it was reinterred in the Holy Cross college cemetery.