| Named By: | Harry Govier Seeley in 1898 |
| Time Period: | Late Permian |
| Location: | South Africa. Tanzania - Usili Formation |
| Size: | Largest species (R. behemoth) up to 2.5 meters long |
| Diet: | Herbivore |
| Fossil(s): | Partial remains of a few individuals, usually of the skull |
| Classification: | | Chordata | Synapsida | Therapsida | Dicynodontia | Rhachiocephalidae | |
| Also known as: | | Oudenodon magnus. Rhachiocephalus usiliensis | |
Rhachiocephalus is an extinct genus of dicynodont therapsid.