Sepidium magnum is a species of beetles of the family Tenebrionidae.
Sepidium magnum can reach a body length of about 29- and a body width of about 12-. This species is among the largest of the genus. Body is brownish-black, while the head, prothorax, legs, and antennae show a pale fawn-coloured pubescence. Prothorax has a large prominent rounded tubercle. The surface of elytra is divided by two longitudinal sinuous carinse, with reticulating ridges on the sides.
This species can be found in Somalia.