John Mary Morin (April 18, 1868 – March 3, 1942) was a Republican member of the United States House of Representatives for Pennsylvania.
He was a delegate to the Republican State conventions from 1905 to 1912, and director of Public Safety in Pittsburgh from 1909 to 1913.
Morin was elected in 1912 as a Republican to the 63rd United States Congress, and served eight terms.
He was Chairman of the United States House Committee on Military Affairs in the 69th and 70th Congresses.
He was appointed a commissioner of United States Employees' Compensation Commission in Washington, D.C., and served from 1928 until his death at age 73.