Joseph Pomeroy Root (April 23, 1826 – July 20, 1885) was an American medical doctor, politician, and leader of the Kansas Free Staters.
After Root was briefly a prisoner of pro-slavery settlers, he devoted himself to the Free State cause, ultimately becoming the chairman of the free-state executive committee.
After negotiating an exchange of prisoners with pro-slavery Governor Wilson Shannon, Root left Kansas to gather funds, arms, and support among Eastern abolitionists.
At the outbreak of the Civil War, Root helped raise units and was a member of the state board for examining medical officers for the army.
After the Civil War Root returned to medical practice in Kansas until 1869, when he became secretary of the congressional Committee on Public Lands.