John James McCook, Jr. (born February 4, 1843) was a chaplain in the Union Army during the American Civil War, and postbellum lawyer, professor, and theologian. He was a member of the Fighting McCooks, a family of Ohioans who contributed 15 members to the Union army.
McCook was born in New Lisbon, Ohio. He graduated from Trinity College in Hartford, Connecticut in 1863. He served in the Eastern Theater of the American Civil War as a chaplain with the rank of lieutenant in the [[1st West Virginia Volunteer Infantry Regiment (3 Year)|1st [West] Virginia Infantry]], a regiment recruited almost exclusively from Ohio. He resigned from the Army in the autumn of 1862 and returned to Kenyon to resume his studies.
As a leading layman of the Presbyterian Church, McCook served at the heresy trial of theologian Charles Augustus Briggs in 1892. He held pastorates in Detroit, Michigan, and East Hartford, Connecticut.
In 1870, he wrote Pat and the Council.