Salterolithus caractaci (Order: Asaphida; Superfamily: Trinucleoidea; Family: Trinucleidae) is a classic British Ordivician trilobite from the North of England in Wales. This is a very fine example of a species now becoming harder and harder to find, nicely inflated and three-dimensional. This trilobite takes its name from J.W. Salter, who wrote the definitive monograph on British trilobites in the 1860s.

The Trincleioid trilobites like Salterolithus are highly specialized, but fall within the Asaphida via their asaphoid protaspides and the presence of the ventral median suture in at least the more primitive representatives of the superfamily. The characteristic morpholgy has a broad Cephalic fringe, sloping outward, bilaminar, with numerous pits on external surfaces, extending posterolaterally somewhat behind rest of cephalon.