Alexander William Doniphan (July 9, 1808–August 8, 1887) was an American lawyer and soldier, born in Mason County, Kentucky. He graduated from Augusta College in 1824, was admitted to the bar in 1830, and began to practice in Lexington, Missouri. He soon moved further west to Liberty, Missouri and gained a reputation as one of the best lawyers in Missouri. He also served in the state legislature in 1836, 1840, and 1854.

While excelling in law, he is chiefly remembered for his military career. By 1838, he had risen to the rank of brigadier general in the state militia. Leading a large force of state troops, he arrested the Mormon prophet Joseph Smith and other leaders and forced them to leave the state of Missouri. In so doing refused to follow orders to execute Smith and prevented vigilante forces from inflicting greater harm to the Mormons. At the begining of the Mexican-American War in 1846, Doniphan entered the United States Army as colonel of the 1st regiment of Missouri mounted volunteers, and served with honor in several campaigns, including the march of Stephen W. Kearny on Santa Fe and an expedition into Mexico.

After the war, he was a moderate in events leading up to the American Civil War, opposed secession and favored neutrality for Missouri. Although he was offered high command by the Union Army, he did not take an active part in the Civil War.