Zanthoxylum clava-herculis (commonly called Hercules' club, Hercules-club, pepperwood, or southern prickly ash) is a spiny tree or shrub native to the south-eastern United States. It grows to 10–17 m tall and has distinctive spined thick, corky lumps 2–3 cm long on the bark.

This species is quite widely used in herbal medicine, it has the same properties as Z. americanum, but is said to be more active. All parts of the plant, but especially the bark and roots, contain the aromatic bitter oil xanthoxylin. This has a number of applications in medicine.