Daniel Ullman, also spelled Ullmann (April 28, 1810 – September 20, 1892), was an American lawyer and politician from New York.

He also served as a Union Army general in the American Civil War, raising and leading colored troops.

Born in Wilmington, Delaware, Ullman graduated from Yale University in 1829 and moved to New York City, where he began practicing law.

In late 1856 Ullman moved into a boarding house that was run by Mrs. Emma Augusta Cunningham at 31 Bond Street in Manhattan.

Ullman's experience as an unexpected witness in a famous unsolved New York City murder mystery was somewhat repeated in 1870, when Major General Francis Preston Blair Jr. was a witness to members of the family of Benjamin Nathan running out of their home for help when they found Mr. Nathan murdered.

After subsequent discussion, in January 1863 Ullman was promoted to brigadier general and sent to Louisiana where he raised five regiments of African Americans as soldiers in a unit that was designated the Corps d'Afrique.

Afterwards he commanded the District of Port Hudson and continued to lead colored troops for the rest of the war, having a full division in mid 1864.