Sphenosaurus is a poorly known genus of procolophonid, a type of prehistoric reptile from the Permian. Originally assigned the name Palaeosaurus sternbergii, by German paleontologist Leopold Joseph Fitzinger in 1840, the generic name was already preoccupied by not one but two other reptiles assigned the name Palaeosaurus. In 1847, Hermann von Meyer recognized the original 1833 usage of Palaeosaurus and moved P. sternbergii to a new genus, Sphenosaurus.

Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Parareptilia
Order: Procolophonomorpha
Family: Procolophonidae
Genus: Sphenosaurus
von Meyer, 1847