John Timothy McNicholas, O.P. was an Irish-born prelate of the Roman Catholic Church. A Dominican, he served as bishop of the Diocese of Duluth in Minnesota (1918–1925) and archbishop of the Archdiocese of Cincinnati in Ohio (1925–1950).

The Diocese of Duluth is a Latin Church diocese of the Catholic Church in northeastern Minnesota in the United States. It is a suffragan diocese of the metropolitan Archdiocese of Saint Paul and Minneapolis.