| James Aloysius Coolahan | |
| Office: | Senior Judge of the United States District Court for the District of New Jersey |
| Term Start: | June 1, 1974 |
| Term End: | July 16, 1986 |
| Office1: | Chief Judge of the United States District Court for the District of New Jersey |
| Term Start1: | 1972 |
| Term End1: | 1973 |
| Predecessor1: | Anthony T. Augelli |
| Successor1: | Mitchell Harry Cohen |
| Office2: | Judge of the United States District Court for the District of New Jersey |
| Term Start2: | April 7, 1962 |
| Term End2: | June 1, 1974 |
| Appointer2: | John F. Kennedy |
| Predecessor2: | Mendon Morrill |
| Successor2: | John F. Gerry |
| Birth Name: | James Aloysius Coolahan |
| Birth Date: | 26 April 1903 |
| Birth Place: | Hoboken, New Jersey |
| Death Place: | Spring Lake, New Jersey |
| Education: | Rutgers Law School (LL.B.) |
James Aloysius Coolahan (April 26, 1903 – July 16, 1986) was a United States district judge of the United States District Court for the District of New Jersey.
Born in Hoboken, New Jersey, Coolahan received a Bachelor of Laws from Rutgers Law School in 1925. He was a law clerk from 1925 to 1927, and was in private practice in Jersey City, New Jersey from 1927 to 1949, including service as a first assistant corporation counsel to the City of Hoboken from 1932 to 1943. He was a judge of the Hudson County Court in New Jersey from 1949 to 1956, and of the Superior Court of New Jersey from 1956 to 1962.
On February 19, 1962, Coolahan was nominated by President John F. Kennedy to a seat on the United States District Court for the District of New Jersey vacated by Judge Mendon Morrill. Coolahan was confirmed by the United States Senate on April 2, 1962, and received his commission on April 7, 1962. He served as Chief Judge from 1972 to 1973, assumed senior status on June 1, 1974, and serving in that capacity until his death on July 16, 1986, in Spring Lake, New Jersey.