William Clarke Quantrill (July 31, 1837 – June 6, 1865) is a Confederate guerrilla leader during the American Civil War.

After leading a Confederate bushwhacker unit along the Missouri-Kansas border in the early 1860s, which includes the infamous raid and sacking of Lawrence, Kansas in 1863, Quantrill eventually ends up in Kentucky, where he is mortally wounded in a Union ambush in May 1865, aged 27.