John D. "Colonel Jack" Henderson was an American editor, rancher, businessman, and pro-slavery politician in the Kansas Territory.
[1] Henderson was born in Pennsylvania but moved to the Kansas Territory, where he became a leading advocate of slavery.
The proprietor and editor of the Leavenworth Journal, he was elected chairman of the central committee of the pro-slavery National Democratic Party of Kansas but was later accused of vote fraud.
He returned to eastern Kansas and fought for the Union in the American Civil War.
[1] In Colorado, Henderson bought a chain of gold mines; on a visit to Colorado, he and some eighteen others were killed during an encounter with a group of Osage Indians for crossing the Osage territory with loaded weapons.