Cyrus Hamlin (April 26, 1839 – August 28, 1867) was an attorney, politician, and a general from Bangor, Maine, who served in the Union Army during the American Civil War.

His brother, Charles Hamlin, was a Union Army major[1][2] who was appointed a brevet brigadier general at the end of the war.

In February 1863, he was appointed the first colonel of the 80th United States Colored Troops and was assigned to field duty in Louisiana.

He was promoted to brigadier general in December 1864 and assigned command of the military district of Port Hudson, Louisiana, Department of the Gulf.

[2] On February 21, 1866, President Andrew Johnson nominated Hamlin for the award of the honorary grade of brevet major general, U.S.