Two fragmentary skulls from the Upper Permian Tapinocephalus Assemblage Zone (Abrahamskraal Formation, Beaufort Group) in Eastern Cape Province, South Africa, represent a new dicynodont taxon. Lanthanocephalus mohoii gen. et sp. nov. is distinguished from other dicynodonts by the presence of a conspicuous laterally facing excavation on the dorsal surface of the postfrontal, by dorsal expansions of the supraoccipital that contact the parietals, and by extensive ossification of the lateral wall of the braincase. Lanthanocephalus features several characters that are suggestive of a close relationship with Endothiodon. These include a transversely narrow intertemporal region, the presence of a pineal boss, and the presence of a distinct boss on the ventral margin of the jugal. Cladistic analysis of a modified data matrix from the literature supports the hypothesis of a sister-group relationship between Lanthanocephalus and Endothiodon. However, this grouping and most others found in the analysis collapse with one extra step, weaknesses that underscore the need for further research on dicynodonts and other non-mammalian synapsids.