William Clarke Quantrill (July 31, 1837 – June 6, 1865) was a Confederate guerrilla leader during the American Civil War.
Having endured a tempestuous childhood before later becoming a schoolteacher, Quantrill joined a group of bandits who roamed the Missouri and Kansas countryside apprehending escaped slaves.
Later on this group became Confederate soldiers, who were referred to as "Quantrill's Raiders".
This group was a pro-Confederate partisan ranger outfit best known for their often brutal guerrilla tactics, which made use of effective Native American field skills.
Also notable, William's group included the infamous young Jesse James and his older brother Frank James.
Quantrill is often noted as influential in the minds of many bandits, outlaws and hired guns of the Old West as it was being settled.
In May 1865, Quantrill was mortally wounded by Union troops in Central Kentucky, in one of the last engagements of the Civil War.