Tetracanthus (Greek "four spines") is an epithet for several different species:
Nandopsis tetracanthus, a fish in the genus Nandopsis Neolamprologus tetracanthus, a fish Scatophagus tetracanthus, a fish in the genus Scatophagus Zelus tetracanthus, an insect in the genus Zelus Echinocactus tetracanthus, synonym of Parodia erinacea, a cactus in the genus Parodia