James T. Mullen (August 30, 1843 – July 6, 1891) was the first Supreme Knight of the Knights of Columbus from February 2, 1882 to May 17, 1886. Mullen participated in the Civil War having enlisted in New Haven, Connecticut in Company C of the 9th Regiment, on September 11, 1861, and became a sergeant in the company. He was honorably discharged on December 27, 1862, due to illness.