Histiobranchus australis, the southern cut-throat eel is an eel in the family Synaphobranchidae (cutthroat eels). It was described by Regan in 1913. It is a marine, deep water-dwelling eel which is known from the southern Atlantic, Indian, and Pacific Ocean. It dwells at a depth range of , and leads a benthic lifestyle. Males can reach a maximum total length of , while females can reach a maximum TL of .