Coelognathus

thumb|Indonesian ratsnake (Coelognathus subradiatus) in [[Baucau District, East Timor.]]

Coelognathus is a genus of seven species of rat snakes in the subfamily Colubrinae of the family Colubridae. The species, which are native to South Asia and Southeast Asia, were formerly assigned to the genus Elaphe. Based on morphological evidence and protein similarities, in 2001, Helfenberger revalidated the name Coelognathus that had originally been proposed by Leopold Fitzinger in 1843. The distinction between Coelognathus and Elaphe was further supported by mitochondrial DNA sequence and additional morphological evidence in 2005.