Thomas Buchanan Dugan (July 27, 1858 – April 27, 1940) was a United States Army officer in the late 19th and early 20th centuries.

He graduated from the United States Military Academy in 1882 and was commissioned in the Tenth Cavalry.

[1] Dugan served on the American frontier from 1882 to 1890, and he commanded a company of Apache Indian scouts from 1884 to 1885.

Until 1898, Dugan served at several locations, including in Arizona, New Mexico, Texas, Oklahoma, and Missouri.

[1][3] Dugan was promoted to the rank of brigadier general in the National Army on August 5, 1917, and between December 1917 and May 1918, he managed a brigade and field officers' school.