Thomas Jefferson McKean (August 21, 1810 – April 19, 1870) was an American engineer, soldier, politician, and farmer.

He entered the United States Military Academy in West Point in 1827, and graduated four years later, standing 19th out of 33 cadets.

[1] Historian Ezra J. Warner noted McKean's unusual situation of having been trained at West Point and served in other duties as an officer, but was as an enlisted man in combat while in Mexico.

When the American Civil War began in 1861, McKean chose to follow his home state and the Union cause.

On June 1 he was appointed the paymaster of the Union Army, and then led the cavalry of the Department of the Gulf beginning on September 18.

McKean was briefly in charge of prisoner of war camps in Missouri, and was appointed a brigadier general in the Union Army on November 21.